Always start low and build up until you see a little nute burn then back off a bit. If you have an EC meter then that will be pretty helpful to gauge how much you are actually feeding em and make sure it is accurate. I just ran a batch of autos and I actually fed them full strength mega crop and they loved it. One of even wanted more potassium. So I'm not sure all autos are light feeders, but maybe mega crop is just less likely to burn in general? Either way, I would start feeding them right away. In coco, I feed a low dose of mega crop and calmag around day 3-4. I usually shoot for a combined EC of 0,5 or 250ppm. Also, just an FYI most photoperiods won't finish flowering in 7 weeks. Very few even finish at the 8-week mark. You are more realistically looking at 9-10 weeks of flowering. If thats gonna mess up your schedule Id shave the time off veg as long as the plants wouldn't be too small.