You can shoot off of strikes and defence. There's plenty of setups. If you opponent has just wiffed, they're more exposed, if you just blocked/slipped their strike, they're more exposed, if you just booped their snoot they're more exposed, if they're in the middle of a strike that the shoot ducks under that will help, if they're mid-spin that's a guaranteed takedown. If their stamina is low, they're also going to have smaller denial windows. You can also setup takedowns in the clinch with trips and throws, etc.
There may be others, but that's off the to of my head. Keep in mind though, it's there's quite a few ways to make your takedown attempts less successful as well
