I found that if you roll up a towel and place it under their arms across their chest - kinda holding them up from the floor a bit - helped a lot.
Yup i was gonna suggest this one!!
Also another thing that I find is good...is when im sitting on the couch, ill put my legs together, and place her on her tummy on my lap, facing outwards so her tummy is in the little indent between my legs IYKWIM ??

Isabell wasnt keen on tummy time at that age either, but once id started using the towel idea, she slowly started liking it, then slowly i took the towel away.
Also my MCHN told DP and I that starting tummy time is good before 12 weeks, but its not essential, its at 12 weeks and after when tummy time is of its most benefit. That could be wrong, but its what MCHN told me.