Some programs (ie, UCSF) are now requiring a passing step 2 score before they will rank you. So you should check with the programs that you're applying for before scheduling a late step 2.
IMO, if you schedule your step 2 for after your initial application has been submitted, then you will probably get your interviews based on your step 1, and then even if you don't nail step 2, as long as you pass it it will be icing on the cake and might bump you up on the list since they know you won't end up failing it in April and delaying your start date.