To get the most out of your auto, you should keep feeding veg nutes until around week 5-6, around the same time that it stops vertical growth. Then gradually take your veg nute dosage back and simultaneously and again, gradually add your bloom nutes in. Eventually you will work off of the veg nutes and fully onto the bloom nutes. See what I mean?
Even though you see pistils throwing out and it's flowering that is technically pre-flowering, in which case you can keep feeding veg nutes to get it to it's max veg state, and then go with bloom nutes to overdrive what's already been going on. The plant will flower with no veg nutes at all, but when you start flower specific nutes, that tells the plant to stop veg growth and focus energy on making flowers. Which can be fine if you have a time and/or size issue, but it's just recommended to do it the way I have explained. If you have any other questions just ask me.