I 100% agree with Mr Big, you need to be 10% or under to bulk...100% ideally and perfectly I'd say 7%-8% is the best BF range to bulk from

If you are a BBer on legit hormones and enough of them, there should be no reason to go over 12% bf or at least much over it... 15% is decently high for a BBer!

Mr Big is also correct that only DNP at a substantial dose would get you down -5% bf in just a month. DNP is horrible for you, so I say do not use it. Just cut at 500 kcal deficit or so and do LISS cardio. If you cannot get down to 10% bf from 15% bf in a non lengthy time frame on 100mg/d Trenbolone ace, 5 IU hGH and even IGF-1 you said you're using + obviously some testosterone prop then you should find another hobby or sport to participate in... something like knitting or bird watching lol :P

Bottom line is that 15% is wwaaaayyyyyy to high to bulk from. You'll end up looking big obviously but just a fat bloated mess at like 20+% that a guy at the same height holding 5 Kg-8Kg less LBM than you at 7% will absolutely destroy you into the ground