Here is my theory, but I've never personally done this so I can't back it up:
You basically want the slin and hGH hitting you right after you finish you're workout, so take the slin as soon as you get back from the gym and take the hGH before you leave (and vary the time depending on how long you plan to workout, where you inject, and how you inject).
If you inject subQ, your actually not going to peak until about 6 hours after your injection (
https://www.pfizerpro.com/product_info/genotropin_pi_clinical_pharmacology.jsp). So, basically plan on injecting six hours before you plan on using the slin.
If you inject IM, it depends on where you inject (
**broken link removed**. If you go with the thigh, then inject 4 hours before you plan on finishing, and if you go with the abs, then inject 2 hours before you plan on finishing.
So in conclusion I would recommend trying this: Inject IM into the abs 45 minutes pre-workout (assuming your workouts are for an hour and it takes you ~15 minutes to get home) and then inject slin as soon as you get back from the gym.
*Want to thank Vad_B and BlueHazard for helping me find the peak times with this.