Remember to drink LOTS of water (and I mean 2 litres at least) on the day of your flush (it is safe to drink water up until 1 or 2 hours before your first Epsom Salt drink, and healthy too!). And the day after, drink LOTS of water again. You can eat something almost immediately after your very last Epsom Salt in the morning. Start rebuilding.
OH yeah...it is absolutely not necessary to have diarrea before you go to bed. Many people don't. I don't. (but then I only take 1 tsp of ES in each of my 2 drinks the night of the flush) So, no need to worry if you don't go to the bathroom after your first two es's!