If you are a beginner...
..and almost everybody who has just read Professional Blackjack for the first time is, then the end result is not whats important. Remember, counting gives you a long term edge, but you arent necessarily going to win money in the short term. Your first few sessions especially, you want to be more concerned with your counting performance then your financial performance. It sounds like you were a bit bumpy at first (and we are all or were) but came around nicely.
Its nice you won your first time out though! Congrats, but dont expect this every time. My first table I won $280 spreading 5-25 and that was the start of a wonderful trip. The next trip, I lost $1000 and my counting skills had gotten much better! It is the nature of the game, so try not to get too frustrated after a loss. When you take a big one, think back to any mistakes you made, if you made few then you should still be proud of a good session (even if it still stings a little bit). If you made many, these will almost always add somewhat to your short term negative fluctuations. In this Ive found it helpful to take a month or so off from BJ, work on the major mistakes you made re-read some of the excellent books out there (Prof BJ included) and go get em again!!
Best of Luck.
D