odds of getting first choice?

So it's extremely complicated. I would recommend checking out the info on NPC's website about RSFB.

But the simple answer is it depends on how high each house rated you. I will say that the way the math works, your preferences matter more than other rounds. So technically your first choice gets more weight than your second and your second choice gets more weight than your third, but based on how many other PNMs also ranked your top choice first and where you are on your top choice's list, it really depends.

I am glad you have the attitude of accepting any house you get though. I promise every house (including top tiers) has members who were originally disappointed on bid day. Seek those members out and find out why they now love their house. Also, each house changed with every new pledge class. Make friends in your pledge class and shape your new home to be what you want it to be. Get involved and it'll be a great experience.