Blooming

You should certainly start her on some bloom nutes since she's now in pre-flower! And your plan sounds like a very good one in that the fish mix will still be giving her some nitrogen to help her grow a bit bigger. I would look at the recommendations made by Bio-Bizz for feeding amounts and reduce them somewhat as autoflowers generally don't take heavy concentrations of nutes very well. You can always adjust the dose upwards later if you think she needs more... Good luck to you and the little lady!!