What OKR to start with?

How long-term should OKRs be? We just launched our sales, it's now presale offer to be exact, and I don't know should this presale flight have it's own OKRs or should it be part of my big plan for what? This year, next three years? Please, let me know what is your standard, since I have to report to my investors and I'm confused with possibilities even though I've read many interpretations before. Thanks!