No, that would be unwise. Getting a ranking on the first page is just one battle won. You need to maintain that ranking. Without consistent efforts in SEO for your website, your ranking will slowly but surely decrease.
Months of effort would end up going to waste if you decide that you will discontinue SEO after reaching the top rank on the 1st SERP (Search Engine Results Page). So if you wish to maintain your ranking or position at the top of the 1st SERP, please ensure that your SEO remains consistent throughout and that you do not under any circumstances discontinue it.