If I don't like the shape after getting fillers, can I get it corrected right away?

I'm thinking of trying fillers for the first time.
I thought it would be good to know about these aspects even before the procedure.

I do have a specific shape in mind, but
You know, when it actually goes on your face, it might feel different from what you imagined.

Especially since it is difficult to see the exact shape at first due to swelling
I am also wondering if it is not possible to make a judgment immediately in that state.

Wait a little while, and after the shape has settled,
Are we proceeding by making modifications if necessary?

Since it's my first time, I'm hesitant to put in too much.
I really just want to improve it a little bit.

For those who had fillers for the first time
I'm also curious if you decided exactly what amount you wanted from the start.