A Question On Re-Dosing Timing?

[doresy]

Ok, here's a question
 
I am at present treating my (now blue) tank for white spot with Interpet treatment.
 
I added the correct dose at 5 o'clock today (Friday) and the instructions say to add second dose on day 4.
 
So my question  (hopefully not being thick!)..........
 
is Friday day 1 so Day 4 would be Monday (thus 3 days between doses) or
 
is Friday day 0 so day 4 would be Tuesday (thus 4 days between doses)   

 
Basically do I add a dose at 5 o'clock on Monday or Tuesday?

 

[eaglesaquarium]

I believe Friday would be considered Day 1.  So, 3 more days, would make Monday Day 4.  We all have those moments sometimes.

 

[doresy]

I believe Friday would be considered Day 1.  So, 3 more days, would make Monday Day 4.  We all have those moments sometimes.

 
 
My wife is in that camp, it was me that questioned it (being naturally awkward 

 )