Your goal should be to regulated the amount of AS in your system at all times.
The shortest acting esters will be in your system for about 2-3 days...... so you should try and evenly space your shots...... ie two shots a week.
However, I suggest that you take a shot of Sust every third day at the least.
There is a good post on this board that is titled 'a new angle for sust' or something like that...... I suggest you check it out