I would approach you question from two perspectives; Safety & Dosage (inc route of administration)
Safety A: Is it really MDMA? I would recommend you reagent test it & speak with others who have had the same product. Is it racemic MDMA (desired) or S+ MDMA or R-MDMA (they have slightly different effects)
Safety B: If you have established that there is MDMA within your powder, then place a small amount on your tounge and spit it out. Generally, and I'm erring on the safety side, any allergic reaction to other materials present in the powder might manifest. Wait 3 or 4 hours and see how you feel.
Dosage A: Make a line approx a Red Head's brand match long and wide. Flat, not heaped.
Dosage B: I would recommend trying the least bio-available method being Oral...as most of it will have to pass the liver first. Also, should there be other materials present that you maybe allergic to, but didn't appear in the 'taste test' then your body may purge it.
This may sound rather laborious but with materials that you did manufacture yourself, or did not originate in a controlled laboratory environment, then your first and only concern is safety first.
Your safety is paramount.
Good luck with said powder!