My approach for both Japanese and now also French has been to wait until I get frustrated because I don’t know enough grammar and then study grammar…
Contrary to a lot of people it seems, I find grammar a lot easier to pick up when I:
- know a bunch of words already so I can focus on understanding the grammar points being taught
- have gained some measure of intuitive understanding of the basic grammar. (For example, in French ~ons and ~ez already sounded intuitively like first and second person plural form to me, so that’s two things less for me to just have to blindly memorize)
Horses for courses and all that, basically…