From my knowledge (ive used clen/t3 for years before I started aas) You can only use clen for 2 weeks. After this your beta receptors shut down and the clen is no longer effective. Both keto and benadryl (via a complicated chemical pathway) keep the beta reseptors responsive for longer so that you can stay on clen for up to 6 weeks.

Ive used up to 100mcg of clen a day - but start lower and taper up - you will here stuff about tapering down but there is no point - think about it- if your receptors are done in what good is tapering down?? Anyway after 2 weeks add the keto/benadryl and then keep both going for another 2 - 4 weeks. keto/benadryl may make you tired so take at bed time (this may be a good thing coz the clen can keep you awake). I would take clen in the morn.

If you want the biochemistry of all this let me know I will give more info.
Oh and have you ever done ECA stack? Effects very similar except clen has longer half life of about 72 hours.
Thanks

2wks on/2wks off seems to be the standard (while using ECA on the off wks)
Ketofin is also an option (from what i've read) so you can just cycle clenn all the way thru
i would try and burn what u can natty thru diet and cardio before u go this route (discipline and hard work are the true miracle workers)

Well Clen is not a miracle worker. Your diet is still gonna have to be in check, which probably will amount to the most fat loss. I would start at 60mcgs for the first 3 days, and then up it up over time, but not exceeding 110 mcgs. (That was my stopping point) Many people do 2 weeks on, then benadryl for 2 weeks, to clean up the beta receptors or something, and then back after 2 weeks. This is off the top of my head, so dont flame me people if I missed something. Oh yea, take it in the morning, because you will be shaking like a mad man!

edit: Did register too early to get the +5 automatic rep?!?!