You know you're doing things right when you're slogging through comments like this:

Okay, WI?* (v2) 33, which diverged with UXM* 137, established that Rachel Summers was conceived during UXM 132. This is assuming temporal parallelism, but Rachel was noted as being nine months old during the events of Secret Wars I, which means that they took place eighteen months after Kitty joined the team.

Yeah, but assuming temporal parallelism gets you into all kinds of trouble.

*What If?
**Uncanny X-Men