I have heard that between 24 and 48 hours is a good length of time. I plan to add the virus to fresh media with serum and antibiotics, wait 48 hours, and then change out the media. I am performing this on a 10cm dish.
Also, is there an optimal confluency at which to carry this out? I plan to transduce cells at 50-60% confluency. My cells peel off soon after reaching 100% confluency. I want to make sure that transduction fully takes place before I change the media.
On the same dish, I plan to add puromycin (my selectible marker) and pick colonies for single clone expansion.