get above a 730 or so on the GMAT, you could probably get away with one year.

Take the GMAT whenever you have time to. I was out of school for ~4 years when I took it. Others took it right after graduation. Like was mentioned, it's good for 5 years so the only thing you are out if you take it now and don't do well is money. The experience will be good.

BYU actually has an excellent GMAT prep program. About half the price of others. I didn't take it myself (I was a self-studier), but everyone I talked to who did the course raved about it.

If you decide to just self-study, I spent hours researching the best materials and I can give you some good advice. The official GMAT study guide and the Manhattan study guides (especially the Number Properties and Word Translations) are golden, along with the PowerScore Critical Reasoning Bible. I raised my score 80 pts in 4 weeks just studying those. The Manhattan study guides give you access to 6 online practice tests which were the best practice tests I took.

Good luck and hit me up if you have any other questions.