Part of this is a timing thing. you want to try to lock legs before you actually want them to lock. You should end up locking legs with your cranks more or less level (9 and 3 oclock) but need to start resisting sooner than that. For me, it worked to think "lock up" when my front foot (which would become the back foot) was around 5 oclock. Dominant leg back works best for most people. Pull up on the front foot, too, can't emphasize that enough.

SO RIGHT BRO