I normally get my labs drawn the day of my shot - before I take my shot. It should not matter too much which day you get it drawn - as you can factor in your timing with the results.
For comparison it would be good to get your tests on the same day each time.
If you are drawing on Friday, you may want to do it before your
HCG, then this would indicate the lowest level of T for the week - as you'll be adding
HCG after the shot.
Does your HCG come with sterile water ? or Bac Water ? Bac Water should make it last longer - maybe up to 60days.