Will you wait this long if you need to do the main quest in order to learn the shouts?
I'm not in any hurry to "complete" the main quest, and I will probably complete a couple of long playthroughs of hundreds of hours without ever finishing the main quest.
However, certainly, I will start the main quest and progress by finding word walls and dragon shouts, etc.
It depends a lot on the story of the main quest. I might be enticed to complete it during the first playthrough, but in Oblivion I played the game a few times without ever really getting very far in the MQ.
Certainly at the very least I would hold off on finishing the main quest until I'm ready to permanently retire the character. Even though you can continue playing after the main quest, IMO it feels like the end of the game. Not going to do that while there are still hundreds of locations to discover, hundreds of side quests, factions to join, crafting activities to master, etc.