I have a 6 month old female cane corso when will she have her first heat?

You can expect your Cane Corso's first heat anytime within the next six months to be honest, my friend's Cane Corso had her first heat at 10 months.

You may notice a change in her behaviour and her nipples will get larger,  It's obviously totally up to you, but if she is 'just' a beloved pet, and you are not thinking of breeding her, it may well be worth considering having her spayed for two reasons:

1. The mess of a heat can be a pain, especially with a bigger dog. Plus she may 'not be herself'. My female dog tries to mount my female cat when she is in heat!
2. Spaying reduces the chance of cancer and other nasties that she might get when she is older.

I hope she is okay with her first heat, I am sure she is gorgeous :-)