hmm I wouldn't use during pct or after.
I would use it WITH the PH cycle. Its not going to be necessary unless you are running a long enough cycle to shut you down completely.
HCG keeps an artificial LH signal so that you maintain endogenous T levels. However, this LH signal can compete with your pituitary and shut it down just like any steroid.
The ultimate goal of HCG is to restore testicular function on long cycles that cause atrophy so that your body has the necessary testicular function to resume its own production when the pituitary comes back on-line.
However, when using an oral only steroid cycle which causes complete suppression like Superdrol or the likes, even tho the cycle may be short and not cause atrophy, you will experience side effects like libido drop etc. Ideally you need Testosterone to fill this gap. However, The HCG can help to keep your T pumping during this time period, however it may make PCT a bit rougher if you weren't already shut down.
In the end, if you are shut down from the PH, using HCG isn't going to make things any worse. Just make sure you drop the HCG before using the SERM.
If you choose to use HCG, personally I think it takes a week or so to get into the system. I would dose it at 100iu EOD a week before the cycle and continue throughout the cycle, stopping at PCT and starting clomid.