The spawn rate of Bro-mons isn’t just a timer, it’s a timer combined with the frequency you visit new websites, so just go onto google and search up whatever you want. You never know, a Bro-mon might just pop up.
Also, if you see a Bro-mon that is a low rarity, let it run away and a new and better Bro-mon will appear about 5-10 minutes later.
[Information by @kaiser]