After is more suitable than once for a sequence of actions that come one after the other. Use once to mean one time.
Preferred |
Discouraged |
After you save the document, you can close the program. |
Once you save the document, you can close the program. |
You only need to perform this configuration once after logging in for the first time. |
You only need to perform this configuration one time after logging in for the first time. |
