Hey Patrick! Welcome to the board!
If you’re just starting out, it might be best to place both fingers down at the same time. As you progress, you’ll think about it less and less, and the timing of the finger placement may naturally adjust.
This is a skill you really want to nail down before moving on too much more. Kick-offs are an integral part of pretty much every type of banjo playing, and really good pickers get 2 distinctive notes out of each one. I sometimes still struggle and will practice a kick off roll over and over until I can get it sounding right again.