I agree with the comments above, shoot the first legal deer that gets you excited but, at the same time don't feel like you HAVE to shoot the first deer that walks by. Like Allegheny Tom said above, observing deer will add a ton of knowledge and enjoyment to your hunting experience.
Quick story: I grew up in a family that shot the first legal buck that came in. When my oldest son started hunting at the age of 9, he spent the first two years shooting the first legal buck that came in also. When he was 12, he decided he wanted to wait for an "8 point". That year we watched 12 different 1.5 yr old bucks from the stand and he passed on all of them, it was pretty impressive to watch a young kid stick to a goal like that.
One evening in late October a small four point came by and proceeded to tear up a small sapling in front of us. He would rear back onto his hind legs and slam his head into the tree. He had dirt flying everywhere. I leaned over and whispered to my son that I had never saw a deer do that before. My son looked at me and said "That's because you would have shot him first". At that point it dawned on me how much learning about deer behavior I had missed in in my life by shooting the first buck that I saw. It ended up paying off for my son as he shot his first 8 point in early November of that year. It was a little basket rack two year old but, he was excited and I was pretty proud to see him stick to a goal and accomplish it.