Chris, hate to tell you, but saddle soap and mink oil are exactly NOT what you should have put on it. You can't undo it now
Brooks specifically says not for mink oil because it softens the leather too much, same with saddle soap, horse saddles lay on a horse back, bike seats are suspended on rails, you don't want to over soften it.
Brooks proofide hardly is needed, I have the same tiny jar from 10 years ago. I can show photos of my Brooks with lots of years and riding in them, and hardly any sag at all.
the only part of the seat you want to change shape is near your sitbones, the rest no.
Look at the Brooks website, they specifically mention not to use minkoil.
A bit of proofide, then just ride it and ride it. Keep it from getting wet and ridden, and they stay in great shape for 1000s of kms. I'll show you one of mine with probably 10000 kms and it looks a million times better than the saggy saddles shown here.
djb...****. I can't undo what I've done unfortunately but I won't add anymore to the saddle. It's out of my hands now...