Bigger bucker bigger buds.
The more tops you have, the longer veg it will take to have them be big fat tops.
The first month isn't seedling stage, plants grow at different rates, you can't just set an exact date on the seedling stage. And even if you could, a month is long for a seedling.
The veg period starts when rapid growth starts. Id say 2 weeks is normal, 3 weeks is really slow.
The seedling pops up, grows a few inches and starts development on its first serrated leaves, but then stops and doesn't appear to grow much for about a week to 10 days. Most of the growth is going on down in the root zone. Then the switch flips, once you have a few sets of leaves growth gets faster every day and you are well into the veg period by 42 days.
At 42 days, you will start seeing preflowers, male or female, pretty soon.