Generally, here's how it works. It's best for a new driveway to go thorough 1 year's worth of seasons. 2 would be OK but 1 is just fine. After the 1 or 2 years, seal the new driveway.
Now, what you should do henceforth, or with an 'existing' asphalt driveway, is this. Only seal when the 'white' of the stone starts showing. For example, if the street out front is asphalt, or any street for that matter, over time, the asphalt starts to wear off. When it comes to streets, it happens rather quickly because of the large volume(s) of traffic on them. For a driveway, it's only getting 'worn off' by the cars that drive on and off of them. Soooo, when you see the white of the stone on your driveway, have it sealed. (WHen it comes to the streets, they usually lay down a new bed of asphalt. I don't recall ever seeing one sealed.)
If your driveway, for the most part, is still showing black on the TOP of the stone, I wouldn't seal. Here's why - If you seal on a regular basis, when the driveway doesn't need to be sealed, after a number of years, the sealer will accumulate in layers and you'll eventually start tracking it into the house! Ask my neighbor across the street. He had to have a new topping layed because of this! He even told me what I'm telling you, and if you can believe it, he's sealed the driveway TWICE this year!!! (It's 1 year old.) I think he may not have 'grasped' what the contractor told him.
Just to put this in perspective, let me tell ya this. I just hand-sealed a few cracks in my driveway. You can buy different types of maintenance-products for the driveway at any of the Home Centers. (Read the label BEFORE you buy it to be sure it's appropriate for what you want to 'maintain'.) Sure, my driveway looks like a roadmap with all those black 'lines' going all over it. But I don't care because 1) I don't eat on it, 2) I don't sleep on it, 3) I don't entertain my guests on it, and 4) I park my cars on it, and they drip all kinds of 'stuff' on it That's my perspective.
I hope I've answered your question. If you need more 'guidance', Post up.
My best to ya and hope this helps.
PS: After today, I'll be back in on Monday morning ...