There are 1.6 billion people who don't have adequate housing, according to Google, so there are 6 billion who do. If we exclude 1.6 billion from our statistic, there are 1200005-14583292 urinating in bathroom tight now.

So let's assume dumping takes 5 minutes, showering takes 10, washing pets takes (let's assume half of population has pets) 10 minutes, but people without pets bring it down to 5 and all of these happen once per day.
Shaving takes 5 minutes and happens every week. Searching for band-aids takes a minute and happens every week. Brushing teeth takes 2 minutes and happens once per day.
So we have approximately 28-29 minutes per day (including urinating) per day (or 861-891 seconds).

So i did the math and got 59 791 666-61 875 000 people using bathroom every second. Since my average time may be off, you can change the result by using 6000000000/86400*<how many seconds total sum of all actions per day takes>