Like everyone else has already pointed out, VMCAS is opening on May 11th this year, so you can't exactly jump in quite yet. Something I would recommend doing, however, is getting things ready to input ahead of time -- it will save you lots of headache while actually applying. Get a good start on your personal statement and even start an Excel spreadsheet (if you haven't already) to organize all of your experiences along with the hours you participated, as well as important information such as address, supervisor names, and phone number/email, as you'll need them for VMCAS. Perhaps make sure that your eLORs are set in place, too. ISU's supplemental application, if I remember right, didn't actually open up for registration until a week or so after VMCAS opened, but someone can correct me on that. And I actually think that that was only because the new CAS IDs are shorter than the old ones were and so the supplemental system had to be updated.