You're back in the dating world after a pretty long hiatus and are ready to meet the right woman. You've also got a seven year-old son. From your now-dust-covered dating experience, you recall that kid = complication, kid = baggage, and you're wondering "when do I tell a date that I have a kid?"
First, you need to adjust your "kid = complication, kid = baggage" equation and restate it as "kid = reality".
Don't mention that you have a son in the first few seconds of your introduction call, but as soon as it seems natural, share your family with her.
Not telling her pretty early on is like a bald guy wearing a baseball hat to a first date -- eventually your amor is going to find out, and if she's not the type of woman that goes for a family man, then the sooner you air that out, the better. Also, for the right kind of woman, being a great Dad is a very attractive characteristic.