Question about Cycling

Okay, the SpongeBob tank is about 4 weeks old and the Danios are doing
fine. I feed the fish once a day and change the water about every 5
days (50%).

Testing the water the pH is fine, the amonia is very low (almost at 0)
but my Nitrites are very high, over 50, and the Nitrates are very low.
Do I do anything different or do I just wait because it's normal for a
new tank.

We are also going to break down and get a bigger tank, either 10 or 20
gallons, I have a corner that it will fit with a little moving around.
Do I transfer the gravel into that tank to help it cycle? If so do I do
that right away or wait until I add the fish. Will I have to cycle all
over again? Should I make up the tank and let it run for a few days
first before I transfer Boo and Yah?

Thanks a lot for your help,
Klane