The ideal time to start basal rate testing is most likely to be sometime in the middle of the night when bg levels are only going to be controlled by the basal rate and not be influenced by the bolus as well. If basal testing is done in the night, then its important not to drink anything with milk in it like tea and coffee as the milk will change bg levels and people don't drink cups of tea and coffee when they are fast asleep. I don't think Mr G.S of TLAP mentions this but its worth remembering. I tend to do bg testing every hour but do so on the half hour and not on the hour - like 1.30, 2.30,3.30 etc and then change the basal rate if need be on the hour and then that allows for 90mins for the basal rate adjustment to get its effect. Where basal rate testing is done during the day, if you normally drink cups of tea and coffee with milk in them throughout the day, then it makes sense to include these in the basal rate test otherwise you will end up needing to bolus all the time.