An SR-71 as your first build is not a good idea. An SR-71 can be an uncontrollable wild beast - it doesn't have a lot of wing on it to provide stability. I have never flown a plane like this with such a minimal wingspan but I'm guessing it doesn't fly slow real well. If it gets too slow it might just fall to the ground. Fly it with adequate power at all times.

It would be better to have a high-wing trainer such as a LT-40 or an Apprentice as your first plane.

I just now read 5 reviews about the Banana Hobby SR-71 29.5" wingspan. All reviewers liked it a lot but a few said they wished it was less prone to dents and made out of a better foam such as EPO. You bought the kit version? If you had bought the RTF version you wouldn't have to deal with installing components such as the ESC. They're already installed. To get the RTF version into the air all you have to do is:

1. Glue (epoxy) front fuselage to back fuselage. Glue(epoxy) both vertical stabilizers to rear fuselage.
2. Charge your 4-cell Lipo.
3. Go fly.
Note: there are no operational rudders on this SR-71.

Good luck!
oliveDrab
ps: check out this video of a turbine powered SR-71: