If it's your first with trad bows, you may want to shoot the first anything deer that presents a good shot. Buck, doe or fawn.
But after breaking that ice, here's a mere suggestion for "what to shoot".
Instead of focusing on one particular buck, another option is to focus on a particular class of buck.
It's the 10% rule. Focus on the top 10% of bucks in any given area. Age class will typically determine what is the top 10% in any given area.
Focusing on one lone buck can lead to undue disappointment if he's never seen and can lead to resentment if a neighbor kills him, when congratulations is the proper reaction.
I am a member or QDMA and try to employ much of methods into my hunts. Saying that, one shouldn't always confuse antler score with "maturity". Also consider body size and antler mass vs score. One could easily argue that a 250lb, 5.5 year old buck with a "small", 14" wide, stout, heavy beamed rack scoring 120 is a much more unique trophy than a 3.5 year old scoring 135.
More importantly, you need to think about your whole herd situation. How many doe's should you kill?
Every area is different in deer population, hunting pressure and available mature bucks. Some have few deer, some have just the right amount and some are polluted with deer. Some area's have ample 4.5 year old bucks and some have very few that make it past 2.5 years old.
My area still has too many deer per mile, roughly 40-45 per mile and the DNR goal is mid 30's per mile. My area also gets very heavy hunting pressure on bucks and tradtionally a 100 class 2.5 year old buck was "the buck of a lifetime".
Luckily that is changing since the mindset of never passing bucks is changing and we're seeing more 3.5 year old bucks. Plus we now have more food per deer since we've knocked down our local herd from roughly 60 deer per mile in the 1980's and 1990's to the low 40's per mile now.
Our camp policy is, fill every antlerless tag you have available on any doe or doe fawn that presents a good shot and then hunt the top 10% of bucks in that area.
For some area's with low hunting pressure, that may mean focusing on 4.5 year old bucks and older. In another area, that may mean looking for 2.5 year old bucks with a rack out to it's ears.
For my area, that means kill any female deer that presents a shot and look for good looking 2.5 year old bucks and up. If a fluke 4.5 year old buck shows up, by all means take a good shot. But I'd suggest you do that on any of the top 10% of bucks in your area.
One last thought, it's hard to "blast away", as you said in your post, with your longbow. LOL