For long ester test such as Cyp or Enan, the rule of thumb is to start pct 2 weeks after last shot; however, there are aas with even longer esters such as sustanon. in the case of sustanon, it would probably be best to wait a whole 3 weeks before starting pct.
In regards to hcg during and after cycle, the philosophy is that avoiding testicular atrophy to begin with will just make pct that much easier to manage as your "boys" already have had a head start with rebounding. Hence running hcg during the cycle (starting around week 2 or 3) will ensure your nuts do not shut down completely and half the battle is already won.
Running clomid and nolva during pct is fairly common for 4 weeks. Clomid would be 100mg ED week 1, 75mg week 2 and 50mg ED weeks 3 & 4. Nolva would run simultaneously at 20, 20, 10, 10. Several variables could factor into whether this is ideal in any particular situation but I know a good number of people who've ran their pct this way with success.