it is up to you, only costs $5 some people apply many times some people apply toward the 'end' of the timeline.
I applied for mine after I got my eligibility letter (towards the end) and it was helpful to see that my partner's application was sent to VO Delhi, that info sharing was done etc. as I did not have this information before and I got my P1, P2 emails soon after.
I applied for my partner's GCMS notes (overseas dependent) and tbh it does not say anything useful or enlightening lol, her application has been 26 months, est. time is 48 months or something.