For those of you who did CrossFit while pregnant, how long had you been doing it pre-pregnancy?

A co-worker and I are going to take the OnRamp class next month. I'm currently TTC. I know you're not suppose to make any changes once you get pregnant but can continue what you've been doing beforehand... Will CrossFit be a problem if I'm just starting out? How long before I have to tell them I'm pregnant (whenever that happens)? I'm cautious because my coworker can't know...