Kellbell - most places recommend starting at 36wks, but the packaging on my raspberry leaf tablets & all the research that I did on it prior to taking the tablets said any time from the beginning of the third trimester (so 28wks). It's different for everyone though - some people can't take it until later in the pregnancy because it can make their braxton kicks worse, ironically my BHs and irritable uterus have gotten a lot less painful since I started taking the tablets just before 30wks, and i just had my first cup of raspberry leaf tea today and so far so good.