So all mods should not be used till after the unbound quest? Because I want to be able to make sure all mods work in game and its hard to find out when the game crashes after the start of the game though? so I am thinking not to install anything until unbound is over or maybe make one vanilla directory with no mods and one with all the mods and switch over to the modded directory once I am passed unbound? The only other thing is one mod of mine adds new races and does some changes to some npcs but that one would be only one to use in vanilla?

i say after you exit from helgen thats where i install all of my mods opening scene is too important for players who plays with default start if something goes wrong then it might effect your game in future

It depends. Even mods of the same category (e.g., Quest mods) some mods must be enabled when starting a new game (e.g., Civil War Overhaul) while others must NOT be enabled until after certain events (e.g., Helgen Reborn). I would suggest read the mod descriptions with care.

If it's crashing right at the opening wagon scene, I recommend you find the problem before you proceed. Disable/enable mods until you find the culprit. You can just start a new game each time.

After you find the mod, you can go back to the author page and see if theres updates/patches or simply get rid of it.

If you use a mod manager you can organize it by when to add mods. Have them ready to install and when you reach point A just add them in, and so on.