Opening preparation

I recently switched several of my openings and was wondering how long people generally take to prepare and study them prior to playing in live OTB tournaments? I figure that I should get a general sense of the many different major subvariations within this opening, go over several games and then start playing in tournaments and only then start delving into all the tiny subvariations. For example: the nimzo indian as black, I would first get an overall move order down pat for black's response when white plays 4. Qc2, 4. e3, 4. f3, 4. a3 etc. and some sub variations that go with each, then restart playing tournaments and in between each tourney review what if any problems came up with that opening during the tourney and learn some sub variations associated with each. Is this what most people do? I figure it could take a really long time to learn everything and that's too long to stop playing tourneys for which would stifle improvement? Thanks

In one of his books about an opening, GM Nigel Davies wrote (2005), "The way I suggest you study this book is to play through the main games once, relatively quickly, and then start playing the variation in actual games. Playing an opening in real games is of vital importance - without this kind of live practice it is impossible to get a 'feel' for the kind of game it leads to. There is time enough later for involvement with the details, after playing your games it is good to look up the line." For the 2015#6 issue of New in Chess, Parimarjan Negi wrote, "You can't fathom all ideas from reading a book, or listening to a coach, or playing through classical games - you need to actually play the openings. Everyone knows a few opening moves, but beyond that, you need to be willing to play these lines, and try to find the best moves yourself, so you can test the ideas you know and get a better understanding of them. If you do well in those attempts, it's great, but otherwise these games serve as important lessons that you can analyse and learn from. I have played the Najdorf for many years now, with more than excellent results, but I remember I almost gave it up at the very start because of a string of losses."