A strategy worth considering:
Assign everyone in the cast a number and use that, instead of cast names or initials, in your blocking book. So F1, F2, F3...etc for female, and M1, M2, M3...for men. These assignments can be based on whatever makes the most sense: I've seen them done simply alphabetically, or in obvious casting (putting the principals as the 1,2,3, and lesser characters further down. Or clumping cast members you know will be staged in the same scenes numerically close - for example: you know there are featured tumblers for the big dance number - so assign them M7-M12).
Then make a cheat sheet for yourself and your team, and, after a day or two of blocking, the numbers will be second nature. I've used cast numbers for a few large-ensemble shows, though admittedly, I haven't done it in a while, and found it really helpful during huge staging sessions.
These numbers can then be tracked through into the tech process, and given to costume, sound, spots, for easy ID & labeling of costume pieces, tracking, mics. This is a very common technique on tours, where crew changes every week.