This would just be a massive time saver - a simple "delay by X turns" like deadwoodjedi has on his calc. Two examples of where this would help me personally:

1) On UNM, my rotation requires me to delay my Martyr's A2 by two turns. This isn't presently possible - I can set my A3 to be the opener, but I can't force it to use my A1 on turn 2 in order to delay my A2 by two turns. If I instead set A1 as opener and A3 as priority, it would let me get my rotation correct, but then would eventually mess up on a turn where I have my A3 ready for use when I want to be using my A2.

2) On NM, my rotation requires me to wait two turns to use my Brogni's A3, and three turns to use my A2. This is simply impossible currently.