How about another suggestion - possibly too late for this training session, but this is what I would do:
Run for 2 hrs only - have 2 sessions - this allows them to go away, finish their nappy and come back to tweak the results or finish if stuck somewhere. Takes the pressure off that one class and allows them to have a go, in their own time, without distraction. Also if they are successful on their own, they are likely to keep it up. (I would assume that the average interested seamstress is a little savy with a machine)
Run another session for those that aren't - preferably within the same program, on their own though, ie week 1 - getting to know a sewing machine, fill the bobbin, thread the machine, variety of stitches, general use and also how to care for...
Be kind to yourself and to other attendees, Breastfeeding mothers only to bring babies. And I mean those that will need a feed in that 2 hr gap and travel time of course. Encourage them to find a sitter, use daycare, rope in gran, aunty or friend (take turns, one does it this time then the other next time - if this is the only option for a lot of them, then run two class -after each other - I mean finish 2 x 2 session, Have a aweek off then run another lot, anyone still struggling welcome back also). The best thing to remember is it will give them a break from the kids and they will focus and nobody will feel cheated. If the bulk of your Mums are breastfeeding, then get in at least 2 highschool or uni students and hire a separate room for day care, baby sleeping, nappy changing etc.
Allow (for yourself) 2 & 1/2 hrs for the class - Gives you time to set up and also wind down, there will always be one or two that hang around to ask questions at the end. (Arrive 15mins Early, and leave 15mins late - but be firm about packing up time, no matter where you are up to, that is why you are having 2 x 2hrs sessions or a 1x2hr and then 1x1hr with maybe the 'learn about your machine' can be before or after the second session).
But - Tell your class, that you will be there 15mins before hand, nominate anyone who is keen to be there at that time and not too much to worry about, to provide flasks of hot water and the makings of a cuppa for those who have travelled (lets the mum who likes to be organised to target an early arrival and time to settle herself and bubs) and also let them know if they would like to run through cutting out - assuming you have already cut out - then you can run through the basics at the very start, so they will need to be there on time! Allocate 15mins to this and then start in with the lesson promptly after that. The Cuppa provider is to be in charge of welcoming late arrivals, settling them in, offer that cuppa and try quietly to not interrupt the rest of the class. If you are going to do this in 2hrs, you will need to stay focused - no going back on what you have just said. Any late arrivals will have to rely on other attendees or yourself later to catch up. Allow time for sewing, it really should be the bulk of your lesson, with you wandering around encouraging and prompting. Suggest they can bring their own machine, but also make it clear that part of the lesson is sewing at home too. If it is too hard for a mum to lug machine and baby and all the rest, she may stress too much and then you will have fun making sense to her. Have your own and another machine there, these ones can at least have a go at the 'intricate' parts of sewing.
I would settle for white only PUL, maybe a selection of linings that they pick and choose from. Or if you do a selection of PUL- so they get to see the yummy choices - First in - first served.
Keep it as simple as you can. This is not the time to be a people pleaser and overload yourself with meeting too many demands. No matter what they get, it will be their 1st home sewn nappy, it will be special no matter what colour and next time they can be picky and selective. Also sometimes they don't know what they want, and it becomes over load for them.
Fitteds are not too different from pockets when it comes to the basics, so invite those ones along, but they will not get to make one till next week, if they require your help. Get in the necessary fabrics, cut out and if they can get the gist of it from the Pocket session - let them go for it.
If you do not need to allocate time to 1st time sewers, you could have 1st hour of second class allocated to fitteds. This means they all get to know the lot, or can pick and choose the times they are there.
Be strong on (NO) coffee breaks, don't tie yourself up with a gossip session, if many have travelled long distances, either buddy them up with locals or find a good coffee bar (beforehand), they can progress to for 'after' discussion sessions.
If you become too exhausted and have too much on your plate, you will loose your focus and this will disappoint many of them. Too long a sessions will be tiring, and eventually they will stop taking it in, it will also allow for too much casual talk and again loss of focus. Although we all want to be friendly, they are there to learn to sew a nappy. If they want a friendship circle, that is what a nappicino is for!
O and if you are precutting stick to Mediums, for everyone (a small baby will grow into it) unless of course they are all NBs
And I would also suggest that you do not have this at home - or at least not at your own.