I suppose the later that you do it, the better but most of us seem to be POAS addicts (I know I am). I did one of those last month and on the box it gives percentages of ppl who got BFPs at certain times (well the one I did had that anyway), you can test 4 (or was it 6) days before your AF is due. I'd save it until you are a bit further down the line and use IC for now.