I got my card on Rounding Third at a regional theatre that I'd been working as an ASM at for a few years. I had been EMC and could have gotten my card earlier on points but glad I waited for a show that was a good match. A small show, 2 actors, minimal automation, a director I'd worked with many times. It was the first time since college that I was SM (vs. ASM). The PSM of the theatre actually served as my ASM, sort of Stage Managing with training wheels which was brilliant - she's an amazing teacher and always knew how much rope was just short of hanging myself - she knew which mistakes to let me make and which she should step in and prevent. I was really lucky!
My favorite day: the show is about 2 Little League coaches (I played several years as a kid) so one day, rehearsal was going to a Little League game, watching, talking to the coach, parents, etc... One of those days of "really, this is what we do?"