When they say the PAVE exam is offered 3 times per year, they mean once per semester. You take the PAVE qualifying exam in your 6th semester here, and if you don't pass you can re-take it in 7th (but there's an 85% first-time pass rate here, so that's comforting). When you pass the PAVE, you get a certificate and that certificate, along with having passed your clinical rotations, qualifies you to take the NAVLE during your senior year. There are 28 states that accept the PAVE (Maryland is not one of them, but I
think that VA is), and other states are working on changing their legislature to accept it.
The other exam that they're referring to is the ECVFG, which is run by the AVMA, and therefore accepted by all 50 states. The ECVFG isn't taken until your senior year, and it's a 3-4 day exam, including hands-on clinical exams.
Whichever one of these exams that you take, you still have to take the NAVLE. Basically all these exams do is say that you're up to snuff with someone who went to a US (AVMA-accredited) school. The PAVE is nice because it's cheaper ($1000), and doesn't involve a grueling 3-day process, but it's not accepted everywhere. The ECVFG is accepted everywhere, but sounds like a pain in the butt to me, and costs $6500.
We just had a seminar about licensure last week, so I'm a font of knowledge.