its a slippery slope man, where do you draw the line? your a young guy right do you want to end up on HRT.Its not a race man just run your time off properly that way you won't risk permanently affecting your endocrine system.
What compounds and esters were u using?(obviously this effects when your pct should begin)... Did you run HCG on-cycle or during PCT?
If you were on-cycle for 18 weeks and ran a 4 week PCT then you should be OFF-cycle for more like 22 weeks!