Both my kids hated it. So I would work them up slowly. I might be with her on the floor and every so often when I remembered I'd turn them over with me near them and talk to them till they complained and then try again later. It wasn't timed as such, it was more about getting them used to it. TBH both of mine hated it until they could crawl. But that's just my kids... not every child is the same

Tummy time isn't just about strengthening their necks it's about stopping them from getting flat heads too by constantly having pressure on the backs of their heads. Not everything is a conspiracy against mothers and babies.