I also am a DWC grower. It's funny, my research on this issue on the internet has been all over the place. I've seen sites recommend bloom nutes from seed, I've seen veg nutes until bud formation and everything in between. I have only grown one auto and I introduced Bloom nutes as soon as it began to flower with decent results. This time around I am going to wait a bit longer to see how the results differ.
See how your plants respond to increasing your nutes a bit.