it has to sit overnight. If you rush it you will just have impure stuff. Dont rush the fumaric acid precip phase..add it and then let it sit all night and check it in the morning.
The sodium carb part was bunk for me every time.
Also when you add the fumaric acid..the stuff that drops out right away is very impure and I dunno what it even is. I just poured off the solution asap and left it in the bottom of the jar and then let the rest of the xtals precip over night and they were all long needle point amber xtals.
Again..rushing is your enemy.
Long live the unwoke.