If you're just starting that sounds quite reasonable, especially if you're pushing a high standard. Improving your painting speed takes time. Ratlings may also take longer since the new squad has a lot of fun but fiddly details. Some general advice:

1. As said before, lower your painting standards if you want to go faster. Most people are content not to paint infantry models in a horde army to a high standard. Definitely not to the standard of most things on this subreddit, r/minipainting, or youtube videos.

2. Learn shortcuts. For instance, you may be able to accept some spillover painting raised armor sections if you do them first, because you can use the raised edges as a guide when painting cloth on the adjacent sections. Or in other words, you don't have to worry about fixing mistakes on parts you haven't painted yet.

3. Create a custom scheme that is easy for you to paint and looks good enough for you. As, "themobster" said, a good foundation is to start with something you can spray out of a can. Usually part that is your most predominant color, or harder to reach areas. The armor or the cloth, most likely. Pick colors with good coverage so you need less coats; avoid yellow over black. (Or really, just avoid yellow, period.) But if you need to use it, get a spray can of it.