This is a general question. You may get a response within a week depending on the reviewer, but this is very unlikely. Now in more detail the generally accepted time frame for journal is about 3 weeks. If a reviewer cannot complete the review within such a time frame, he would be expected to decline to review.
Reviewers reply with comments and can basically recommend a) straight acceptance, b) straight rejection c) acceptance or reconsideration after some changes made by the author(which may involve a substantial amount of work-after all the reviewevr may require the author to prove something important that the author has not shown) and d) acceptance after minor revisions.
If changes are required and the reviewer needs to see the manusctipt again, then typically the bottleneck is how fast the author sends in the revised manuscript, not the other 3 weeks or less to review.
Keep in mind that some journals use 2 reviewers.
Typically the more revievers the journal uses, the longer it takes on average.
So bottom line is it varies, but you should expect 3weeks-1 month. But why are you so worried about this time? The time to review is a tiny fraction of the total time it requires to do the research and also the time from acceptance to publication