For a lucky few, it's entirely possible to get straight into the RHS of a B757 on graduation from flight school. Many will go straight to a B737 or A320. However, there will be many more who don't! You still have to be lucky - and you have to understand that you are missing out on a great deal of good flying by going straight to a modern jet. In an ideal world there would be a more structured (and fun) route to jet flying, but that's not how the market works. Still, those who do manage to go via the 'traditional' route of FI, air-taxi, commuter and then jet will have more fun on the way than those who go straight to a 320 or 738, and will not regret their choice when the time comes for bar-room story-telling in their twilight years!
Scroggs