I'd love to chime in here! Could you you please explain your statement a little more for us? From my understanding, you're asking about those who *view your content and would have a 90 day window about considering to buy it.
Although you want sales as quickly as possible, you want to remember that customer need to engage with your content 4-7 times before the majority will initiate a purchase. You mention that "if they won't buy they won't" but that isn't necessarily true.
If they view your content, there is some small part of them that has had their interest peaked. Once you show those ads to them (or even content) a few more times, you can make that grow until they eventually do check out the store and initiate a purchase!
If you could go into a little more detail about what you meant however, I'd love to continue discussing it.