I should try it and see.
Sorry if that sounds glib, but the truth is there are so many factors (fitness, muscle mass, stress levels, recent food intake, intensity of exercise) that it is impossible to say.
Are you prone to hypos?
I am, and exercising before breakfast is (for me) a VERY BAD IDEA.
Likewise 'car loading' before exercise
that creates terrible crashes!
Other people find it is marvellous.
Also, be prepared for a few inconsistent blood glucose results.
Steady exercise generally lowers BG
Intense exercise generally raises it in the short term, then lowers it for several hours.
But guess what? There are a lot of factors that affect this (fitness level, muscle mass,stress levels, recent food intake, intensity...
)
Exercise also (for most people) lowers insulin resistance.
For me, being in ketosis has lowered my risk of hypos, increased stamina and given me far more energy through the day. But of course, I can't speak for anyone else.