For model/year, FSM/Aisin instructions said to set crank at 50* before TDC. Instead, I set up the cam marks to the T's, crank to the dowel on the timing cover/4square marking on the oil pump. Cams did not jump. Hope this helps someone else.
Thanks all for the feedback. I thought it could do damage if the cams moved, but perhaps this is pretty common in belt removal. This, and the T-marks vs I-marks, and 50* BTDC vs ATDC vs TDC etc for belt removal have been my biggest hangup in progress as there is so much conflicting info out...
I've read lots of info about setting up timing marks for VVTi to do a belt replacement but haven't had any luck finding info from people who had success with non-VVTi timing belt replacements. I have the Lexus service manual and Aisin instructions but I need to hear definitive tips from someone...