During the first month of treatment, changes happen gradually. By the end of this period you may notice slight movements of your teeth, although they can be so small that you're not quite sure whether you're really seeing them. This is completely normal.
Of course, every rule has its exceptions. In some patients, the changes are more noticeable not only to them but also to those around them. The younger we are, the faster our teeth can move. In rare cases, significant changes only begin in the second or third month, which usually means that tooth movement in these patients is slower.
After about 4–5 months of wearing braces or aligners, your teeth will be noticeably straighter and the changes will become even more visible.
This answer is for general information. Your own case needs an examination by an orthodontist.