I guess, all I can suggest is keep good records.
Personally, all my females look different so there's no chance for me to mix them up. You can get an ear notch for rats/mice and tag their ears for identification. Sharpie mark on their ear or the base of their tail works too, but has to be repeated every week or two as the ink fades.
To avoid mixing up females, you can categorize their cages as well.
So like,
Breeding Cage
Female 1 Cage: Pregnant
Female 2 Cage: Litter
Female 3 Cage: Rest
You can keep the females in their designated cage to avoid stress and just rotate a cage card that states their status. So for example, when Female 3 Cage is done resting, you can rotate a male into their cage to start breeding. Move the female 2 cage card to rest, etc etc.
You could probably even narrow down the males to 1 and just keep rotating him with the breeding stage cage.
These are just suggestions. In the end, you can do whatever you want.
And females in a group tend to synchronize their heat schedule (like humans), so they'll all go into heat at once...So you may not get a litter a week with this system. If you wanted a litter a week, you may have to make the groups smaller.
This shows a good example of litter a week w/ 12 females:
http://i81.photobucket.com/albums/j2...ngCalendar.jpg
Hope I didn't confuse you.