Autocross and a 904 transmission

Agree. Depending on the course might do like blu posted, but typically put in 2 and and let it do 1-2 2-1 automatically. If you have kit that holds it in 2 no matter what, then start in 1 and upshift.

Most important thing is to practice. You can try a local event - usually SCCA affiliated these days. Moparty probaboly runs theirs a little differently. With SCCA autocrosses, the morning walk is an important part of the game.

Second most important thing for many is to enter the corner smooth, and get the speed down early enough for the tires to bite and turn. Super easy to go in too hot and then complain the car understeers. No. The driver induced the understeer. <embarressed>

Slow is smooth and smooth is fast ;)
Not too slow! Slow enough to be smooth and keep on course. On an SCCA autocross - knowing the course and thinking ahead is critical and also challenging. I expect the Moparty course may be easier to follow (less visual tricks and traps) but the priciples will remain the same.
Stay as close to the critical cones as possible - the shorter distance traveled the less time it takes to finish the course.

https://www.forabodiesonly.com/mopar/threads/any-autocross-racers.378938/post-1972147817