If yo uare going to use scrim then keep them at full size, they are a bit bulky for a while, but they soon break in and you get used to the size of them quickly.
All you need to do is slap them enmasse into the washing machine on the hottest setting, if you haven't got the hemmed variety I wouldn't worry too much avout getting them hemmed, its a lot of work for one thing.
Trying to break in 10 scrim at the same time won't be fun, so introduce them slowly, use one or two a day for wet work, mopping sills and frames and so on, though as you are WFP I guess it will take a little longer to break them in!
Personally,and after using scrim for the last 23 years I think the full size, flat weave microfibre clothes knock scrims into a cocked hat in almost every area.
Tosh lent me a couple of good scrims the other week (I'd lost my micro's
) I don't need scrim or micro often, but I had bought as new batch of ten micro's.
A fully misted up van windscreen - as an experiment I used the scrim to dry a strip and the micro to dry another, the scrim was good of course, but the micro was better by a mile.
so as microfibre clothes are now almost as cheap as scrims I don't even bother buying them anymore..and there is no breaking in with a micro!
Ian