You can if you want now would be the perfect time to do it though with autos you will slow her down. which is probably a good thing for you if you wish to train them like most growers tend to try though. Please keep in mind for autos topping is a very advance high stress training tecnique only really used by people who have done it before and know how the strain will react most growers try this and end up with a tiny yield through stress some may even herm its all about your growing experience with autos some can do it really good others dare not even try just guage it by yourself my friend and never do something for the first time on your only plants try it out on a plant you dont care about first trial and error is near enough the only way we learn for ourselves as growers :) best of luck