Started metformin 500mg 2x/day. Have diarrhea 2hrs after each dose. Will this stop? Can I take anti diarrheal meds? Should my doctor Δ the dose & time

It will stop. It should stop after a week or two. Best way to minimize such side effect is to always take right after meals. If you have this problem persist beyond this period, you can discuss with your physician switching to Glumetza (enteric coated) if insurance can cover.
It Should with Time. Metformin is notorious for causing diarrhea due to its effect in the intestine. Sometimes taking a lower dose at first and working up to the target dose helps. Using a bulking antidiarrheal such as kaopectate is preferred, or simply increasing dietary fiber. Avoid Imodium (loperamide) and other anti-motility antidiarrheals since your diarrheal problem is med related. If all else fails tell your physician.