Yeah when I used HCG (with just hgh) the precum was insane, and the load was MASSIVE, especially with my other supplements (however yes, it would come out within 3-5 mins top, sensitivity felt good tho)
I have also used oxytocin before (peptide form injected with CJC dacless nightly), it was very comparable to hcg but with more of a pump down there.
HCG without an aromatase inhibitor will lead to more downstream estrogen which then affects oxytocin signaling. same thing with regular testosterone-based steroids (not DHT based steroids, those arent converted by aromatase).
I will say oxytocin is not a bad thing nessesarily. If you REALLY want you could try an SSRI or something else, but given that you don't know how hcg affects you fully, I don't think you would be able to take the time to learn the complexities of dosing anything for premature ejaculation
if you have a decent pelvic floor and know how to edge, then with a few supplements you can get a pretty substantial load going, but I don't know if that's your thing. Pairs well with a lot of foreplay and oral