^what he said, just to add to it....they will make your "line" an hour or two prior to the 48 hour window but AFTER TTOT.
You can email requests, the shorter the email the better. You can make up the entire month in trips if its logical if you want, but they might trim the starts/ends off the trip. Your line value after TTOT is protected for your composite. RSV days pay the 3.xx which is almost 4 hours, and add to the pay protected value. You can TTOT once it opens after the start of the month, but you need to call SCHED every single time you do to have them add the days off back in. You can delete days off in TTOT but you can not add them, only sched can.
I got a comp once with 14 days off not flying, and 3 RSV days. I emailed them all the trips I wanted, it was worth 92 hours, they gave me all the seq I asked for BUT they cut off everything but the over nights on all the 2 day trips and it was worth 60 hours with 3 RSV days. I TTOTd the entire thing and dropped 1 RSV day, I got paid 108 hours that month.
Good luck and refer to the contract, remember for 95% of the month, based on the contract, you are a LINE HOLDER.