Starting Dose

Hey guys im starting Reta in a few days. I was taking Tirz 3.75 and want to switch, my last dose jacked my stomach up diarrhea for a week but overall tolerated it well and lost 20 lb in 2 months. I was wondering what does would be a good starting point with reta? I was thinking like 0.5 for a few weeks. (note I been off Tirz for 2 weeks to clear my system.)