If you’re choosing hospital to deliver, should start going for hospital tour once you’re pregnant to find out which hospital you want to deliver at, same as when you start to look for gynae. If you’re following gynae, then the hospital is probably fixed according to where he or she can deliver at. If that’s the case, I would prefer to start around 2nd trimester as it may be tough and tiring to carry a huge belly to walk around in 3rd trimester.
Sometimes available slots are available only a month later and if your gynae practices in more than one hospital, better secure hospital tour slots earlier, less stress later.
You can start as early as when you know you are pregnant. Call all the interested hospital for date. As some hospital date can be as late as 2 months later
Maybe around the start of he third trimester:)
From 2nd trimester onwards.