I used the GH nutes about 20 years ago, before there were many choices, nothing wrong with it. can work just fine. Yes the happy frog will be fine for the first 3 weeks from planting then you will need to start feeding.
I don’t use AN anymore as prices and availability became a problem, moved on to Jacks 123, so much cheaper and works great.
Check out my current grow journal to see what I’m doing now.