is ANOVA the right approach?

I'm conducting a study on the effectiveness of an intervention in reducing procrastination. Participants will be randomized into an intervention group or waitlist control. I will be looking to 1) evaluate the effectiveness of the intervention (reduction of procrastination) 2) examine whether pre-existing conditions moderate this effectiveneess

I've been trying to design the data analysis but I'm not very good at it. So far, I've thought of using a mixed-design ANOVA to compare procrastination scores across time and between groups and a moderation analysis using multiple regression to examine how pre-existing mental health conditions affect ACT’s effectiveness.

Does that make sense? I'd appreciate any advice. I know there might be a problem with missing data for the ANOVA but I was going to go around it with the last observation carried forward. It can't be a super complicated analysis as I simply won't manage to do it. Thank you!