Firstly, I think it's great that you are indulging your partner's cheese fetish, I'm sure he is going to appreciate it and enjoy it greatly!
My cock gets cheesy pretty quickly, here are my tips for getting a lot of smegma :
1. Start with a clean cock, pull your skin back and wash with warm water but no soap. Then once you are dry, have a wank and get your entire cock head covered in cum, then put your skin over and leave for 2-3 days.
2. Have patience and refrain from pulling your skin back at all. Take showers instead of taking a bath and keep your dick pointed down so no water gets under your foreskin.
3. When pissing, pull back just far enough to expose your piss slit. When done, shake very gently, don't pull your dick to get the remaining piss out. If any piss gets under your foreskin it will break down the cheese because it is acidic.
4. When wanking, also don't pull back all the way. BUT when you cum, pull your skin back and get as much cum as possible under your foreskin, then put your foreskin back. Don't wipe the cum off, leave it there as that is what forms most of the cheese over time.
5. It goes without saying, but so sex or getting sucked off by your partner while you are trying to grow it as that will completely wipe it all off.
6. Keep your crotch as warm as possible for the cheese to grow. Wear brief style underwear as this helps to keep things warm and tight.
7. I have found that taking protein supplements makes my dick really cheesy, I think because of the excess protein. I use the whey style protein that you take after working out). It might not work the same for you, but worth a try!
8. The most important thing… PATIENCE! I can't emphasise that enough. The more often you pull back to check, the more air you expose to your cock head and the less the cheese will grow.
I hope those tips help, I'd be happy to answer any questions and would also love to know if the tips work! Good Luck!