Struggling with figuring out when you have "enough" damage in Act 1.

I'm getting to higher ascensions on my non-A20 characters (IC, Defect, Watcher A17-18) and I'm having difficulty figuring out where the "line" is between killing gremlin nob turn 3 and killing him turn 4 (for example). When do you have enough mediocre common cards to live through act 1 but not die in act 2 by bogging down your deck?

Edit: Thank you for all the suggestions!