I think there are a lot of issues you need to consider before making that leap(even if it isn't for a few more years).
As far as I know, most adoption agencies will not, as a general rule, adopt out a child to anyone other than the "ideal" couple(usually referring to a heterosexual married couple). Not that I agree completely with this, but this is what I've heard and seen.
Also, if you do adopt before meeting that special someone, you need to take into consideration how they will deal with this. They may not agree with it, or they may only want biological kids with their loved one etc. People are funny about certain things, and this is a major, major issue. I know a lot of men and women who will avoid dating potential partners if they know they have kids. So, unless you are willing to accept the consequences, don't be surprised by how some women treat you etc when they find out. In an ideal world, it wouldn't matter, but this sure isn't an ideal perfect world.
Also being a single parent is one hell of a job. I'm sure a lot of people on these boards can tell you that first hand.
Who will take care of your child when you're at work, or on days/nights you can't be there? Being a parent involves a hell of a lot more work than a standard 9-5 job. WIth a child you never get a break. They're always there, needing to be taken care of and loved etc. I know, there are a million other points, but I'll spare you.
With all that said, I think adoption is a wonderful idea.( Some of my closest friends were adopted
) It does involve many, many positive outcomes, but you need to seriously consider every single aspect of becoming a parent. The slightest thing can really make or break you and your future.