Noob needs fertilizer help

I have 2 orchids not in bloom. Sitting in an orchid mix I bought from Home Depot which I water whenever it feels dry and I make sure it fully drains.

Every week after watering I put about half a pump of liquid Indoor Plant Food by Miracle Gro. 20,20,20.

So far my roots are beautiful and I have leaf growth.

Am I doing this right? Is there a different fertilizer I should be using?

AND TO DOUBLE-CHECK - I DO NOT fertilize when it's in bloom, right? I killed an oncidium once and I think it's because I fertilized during bloom.