The simplest answer to this question is: it depends. It's been a long time since you launched a website, optimized your title tags, and got ranked in a matter of weeks.
You can't launch a website and expect it to rank near competitive searches in a few weeks. It takes time for a website to perform organically, because Google ranks relevant sites that have built authority. You have to earn your way to the top of Google.
It usually takes anywhere from six months to a year, but it also depends on the level of resources you allocate to your strategy, the level of competition, and what others competing for the same searches are doing.
It can take just a few months to get a page on an existing website to rank high, while it can take years to get a new website to rank high.
John Mueller of Google recently said that it can take up to a year for them to know where to rank a new site, and that fluctuations are expected during this time.