I find that 1-2 days, maybe 3, is a good number before getting a review. This doesn't mean they have to be finished with their piece of work, or that they even

I find that 1-2 days, maybe 3, is a good number before getting a review. This doesn't mean they have to be finished with their piece of work, or that they even have to commit the code at the end of the review, this is just so a second pair of eyes can see it and both can agree that they are on the right track. Then when the functionality is complete, the same reviewer can glance over the already reviewed sections before focusing mainly on the new changes.