Pregnant after IVF approval...not sure when to let Dr's know

Me (almost 36f) and my partner (37m) just found out we're expecting a week after we were told that our IVF funding had been approved.

I've been told by other reddit users that if the clinic calls about IVF to not mention it and delay a while in case the pregnancy fails.

But I'm not sure about how long to leave before contacting a midwife/GP. They say to do it ASAP and before 8 weeks. I am currently 5 weeks and on holiday in another part of the UK next week so was thinking of contacting them when I get back in my 7th week. Is this okay to do? I'm not risking anything by leaving it to 7 week mark am I?