But, you know, AFAICT, most people start up from stops out of the saddle. Personally, as I stop I shift into a gear that I expect to be in on the other side of the intersection and usually to 5-10 pedal strokes out of the saddle before sitting down because the cadence has crossed the standing/sitting threshold, which is about 60-70 rpm for me. And, as I said, on long climbs I'll get out of the saddle when my ass feels like it's been IN the saddle long enough, or, of course, to clear a steep pitch. For the former, I try to keep the power close to what I was doing seated. For the latter, it's whatever I need to make it up that pitch.