I just asked and this is what I got back: (1) if you're sure you want to complete your senior year, just wait till then to apply; (2) if you're not sure, apply now; (3) there's not currently any process for people who want to apply to batches farther out than the next one. I suppose (1) and (2) follow from (3) but there you go :)
Either way, good luck and please do apply when you're ready!
Either way, good luck and please do apply when you're ready!