I started with 35mm and quickly switched to small plates taped into a large format holder. Looks pretty good for a first try. My best developments were with Amberlith, never good luck with pure red or pure yellow gels. Try a north facing window indoors to avoid heat, leave it in there all day it will be fine. Write everything down, number each plate even if it is a failure and take digital photos and keep them recorded with the plate number, even if you polish it away and start over. You will see seasonal changes this way and be able to anticipate how to fix issues when things go wrong. Welcome to the club.