Let's take a look at The NPC or National physique committee.

In all fairness you could go Pro in just 2 shows, possible YES!---Probable NOT LIKELY!
Let's look at the break down...
First show you win a open class Bam you qualify for nationals, then if you win that show overall or first place in your class say hello to your IFBB PRO CARD!

So let's look at the full step progress.
1.) Pick a show but allow 16 weeks to prep esp if this is your first show this gives you plently of time for trail and error and stay above the curve.
2.) Register for the show this makes you commit to doing the damn thing!
3.) Register for your NPC card this allows you to compete at a NPC show!
4.) HAVE ALL YOUR GEAR READY FOR PREP.
5.) Start getting a nice base tan
6.) Have your diet prep planned out the week before you start.
7.) Work on posing every chance you get you want to look like a pro on stage!
8.) Start working on your posing routine the whole prep dont want to look sloppy

This is the basic run down checklist before hitting the stage and making a run to first place!