It’s always hard to let go of your idea or project, to admit that it’s not working and move on.
Our best general-purpose advice here is to beware the sunk-cost fallacy and realize that our egos can get in the way. No amount of investment can guarantee that something is still a good idea (or ever was), and in the long run, you’re often doing yourself a favor by cutting losses and moving on.
But though the same logic applies, it’s especially hard to give up on SEO campaigns. The nutshell reason is that SEO campaigns are long-term plays by their nature, which complicates things. Giving up on an SEO campaign means you lose whatever time and energy went into it—but it also means that you can’t avoid investing that substantial time and energy again.
Compounding the issue: because SEO is a slow play, it’s harder to tell when you’ve crossed the threshold between success and failure. The best SEO work in the world won’t show its full value until months or even years later—so how do you tell the difference between It’s Going Slow and It’s Going S**tty?
After the obligatory “it depends, potentially by a lot,” the linked article gives some general pointers on how soon you should see results for SEO campaigns. As a rule of thumb, you should see something happening within a couple of months, and then progress should start picking up after that.