Space it out.. even though clen does have an extremely long half life it is always best to space out intake of any CNS stimulant.. just make sure you don't take too late in the afternoon or evening or it may affect your sleep.. so i would say half upon wakening.. half after lunch time or so.. should be perfect.. me on the other hand.. can take clen an hour before going to bed and it won't affect me at all.. but then again i can sleep through anything..