I need to add to my gas black pipe supply for a new dryer. I am upgrading and switching from electric to gas since I have the service.

Here is what I know:
I already have 2 capped tees I can tap into the main.
The runs are straight and simple. (Prob just 2 90deg bends)
I know the threaded pipe needs to be doped up and tested for leaks with soap.
I know to have a cut off valve at my destination for service.
I know to use a flex pipe to my dryer.
Obviously turn off the main when doing this all.

Is there any advice for my new branch?
How long does the pipe dope need to set?
What is the min size of pipe I should use?