Your ratings don't say where they came from. Get them with as little debt as you can. ATP isn't going to set you apart or get you ahead. The only thing they'll do is separate you from your cash.
Second, don't expect what they told you. I'm sitting reserve and I'll be lucky to clear 30 this year.
If it's something you want to do, take your time. Get your ratings somewhere that doesn't cost a ton of money, and keep being somebody we all look up to by being a hero. Lots of firefighters in my family. I have the utmost respect for you guys. With the typical schedule you guys work (24 hr shifts) you'll have lots of time to work on ratings, then instruct and build time while keeping a real job that keeps food on the table and puts some cash in the bank for those first couple years.
They covered it pretty good above. Don't listen to any projections especially when they're trying to get your business. Something to consider: Last year I was around the 200th hired at my regional out of a forcast of about 1000 for the year. They stopped around 250 and by September I was on the street.