Anyone have any experiences with "phospho-soda"?

How long does it take this stuff to kick in? If I take it this evening at 7:00 p.m., will I be okay at work the following day?Anyone have any experiences with "phospho-soda"?
The only thing you may feel at work is tired. That is a saline laxative that may take up to a couple of hours to kick in (depending on how much of the bottle you take). You may be up for a few hours after that, however, if you catch my drift.
I just had to use it prior to a test and it kicks in like crazy within about 20 minutes. Stay near the can! Then it keeps making you want to go for I'd say a couple of hours.
If you take it at 7pm you'll be cleaned out by 11pm and totally fine the next day for work.