Welcome to BYC! You'll get lots of support here, and if you hang out regularly, it will substantially lower your learning curve, since you will learn from others mistakes and successes.
No one has commented on the feed issue yet. It appears you're trying to feed different feed to different aged birds? No need, really. When you feed out what you currently have, if you buy an all flock feed, which is higher in protein than layer, as well as tastier to the chickens, it will greatly simplify things as you add to your flock. Just offer oyster shell free choice on the side and the layers will help themselves to what they need.
I have been feeding all flock feed for years now, and I don't have to worry when I have chicks growing up getting into the layer feed which isn't good for their growing bodies, and roosters really shouldn't be eating layer feed, either. Frankly, I wonder sometimes why they make it.
You might also look into fermenting your feed, which makes it go farther and makes available more nutrients and pro-biotics to your flock. It's simple and easy and you can visit the "Feeding and Watering" forum to read through the thread on Fermented Feeds, but if you're interested, I can tell you how to do it.
As far as getting those pullets started laying, and I'm happy to hear one has come around, I jump start my girls along about this time of year with a little light. It only takes a tiny light, I have an electric candle, coming on a few hours before sunrise. Their hormones are being triggered anyway by the lengthening days, but a little extra light will get them started laying faster.
You've noticed increased activity in the nest boxes. That's a precursor to laying. Pullets like to "play house", making an awful mess sometimes, before they get serious. Let them have their way. It's a normal learning behavior. And salting the nest boxes with fake eggs will work wonders, too.
One last word of warning. You may not have given any thought yet to the potential chickens have as great and affectionate pets. Beware. They may bring you under their spell, and then you're a goner.