I'm certainly not a Vet, however HCG should be used both during blasts and when cruising at around 250iu 3x a week.
This is common practice when going on TRT, which is essentially what you are doing. Some users are able to have kids whilst doing this, some are not.
You may find that you can have kids, or you might have to come off and run a SERM for a while to try to restore natural production and fertility.
There is a chance that this will not work and fertility could become a long term/permanent issue after being on for years.
You could check your fertility now and if all is good then use a sperm bank as a precaution.
In my opinion if you are planning to have kids within the next few years then this would be a really bad time to decide to start to blast and cruise. I assume you are in a serious relationship if you know that kids are around the corner then this decision could potentially ruin everything.
I would have some kids then start to blast and cruise, unless you have health issues due to low T currently.
This is just how i would view things if it were me.