Get yourself enough empty boxes to separate all different development alternatives you are planning to use. That way the chances of mixing up the different development alternatives are less, compared to putting them all back into one box and hoping you don't make a mistake in the darkroom before developing.
Normally I would use N-2, N-1, N and N+1, so that would take 8 boxes. You could do with 4 boxes, as you will be able to distinguish the Tri-X and the FP4 by the notch codes before developing. If you ask around this forum, quite a few members will be happy to send a couple of empty boxes for the postage fee.