first off, you should be doing your enanthate shots a bit more frequently...2x a week instead of every 5 days. i know i know..."but it has a 5 day half life". blah blah blah. not flaming you, but we hear that alot here. yes, it has a 5 day half life, but shooting 2x a week will keep blood levels more stable.
if you want to use the prop, you have 2 choices. start it at week 14 once the enanthate is done. shoot 100mg/EOD for 14 days. wait 4-5 days and start recovery.
or, stop the enanthate at week 12 and follow what i just wrote above.
good recommendations for recovery...you can find those in the sticky's posted at the top of the anabolic section. but hCG and nolva or clomid will be needed.
have a nice day