OK, so looking like nitrites are dropping in 24 hours (rather than remaining spiked) but not in 12 hours, right? That, if true, would put you in the phase right after the nitrite spike. During this phase there can be an awfully high buildup of nitrites and nitrates because the ammonia oxidizers are now a stronger colony and have been putting out a lot during the nitrite spike and the excess just keeps building. Now you can do nothing and things will still go ok, but if you're interested in working with your tank some then I think as this phase goes along it can't hurt to do a large gravel-clean-water-change-ammonia-recharge on the weekend, as this will greatly lower the nitrates and nitrites, possibly helping the N-Bacs to reproduce a little faster. Its a trade-off because any time you do a water change during a fishless cycle there will be a bit of a "pause" in the processing, but usually it can have a bit of kickstart effect and things will go a little faster afterward.
~~waterdrop~~