because prop has a 2 day half life, dont mean its in your system for 2 days, that -means 2 days after 50mg its 25g 2 days later 12.5...mon - thurs injections fine, especially for your first time...im 19 and i did a cycle of 13ccs of sust 250 and 10ccs of deca 300 and gained 25lbs and kept 15 with few side effects (maybe some deca dick)...mon/ thurs inj. are perfect for sust!