If it's within the first half hour, it's more than likely just off gassing the oxygen from all the sloshing and such before you put the lid on.
Your airlock is just a vent, a valve to release excess gas, and to keep the beer from exploding onto your ceiling. It's not a good fermentation gauge, sometimes they don't even bubble, or stop and start for environmental reasons (like change in temps or barometric pressure,) or will stop and start because the cat bumped it, or you opened up the lid. So trying to gauge fermentation by it isn't a good idea.
Congrats on your first batch!!!