Three minutes in each bath sounds about right to me - IF you use D23 with a Borax afterbath (the only version I've tried). You should get a fairly well compensated negative, but may lose almost a stop of speed. But that's why you use it, isn't it?

How does Delta 100 behave in this brew? I have avoided it for years, as I find it too sensitive to small variations in development for a sloppy worker like me. But if it responds well to D23/Borax I might well give it another try?