Always gap the points first at .015" at the peak of the distributor cam.
Then time the bike by putting the engine at exactly .8mm(~.032") before TDC, and then rotating the points plate until the points just barely begin to crack open(and turn on a 12v test light if you are using one). Then tighten down the points plate.
If you time it first, and then adjust the points gap, the timing will change.
So, always do the gap first, then time it.