Can yo use a vanilla save to start the game, after STEP install?

[RustyLH]

I noted that they advise starting a new game, but I have a save from right after exiting the cave at Helgen, and it is 100% Vanilla.  I am curious if I can use this.  Is the main objection to using previous saves due to people using saves well into the game, or maybe having a mod or two baked into the save?  I'm just not sure what the difference between this save and a new game would be.

[TechAngel85]

Some game aspects initialize at game creation. This means any mods which alter any of those game aspects usually need a new game for them to be initialized properly. There are a couple mods in STEP that require this such as Immersive Citizens. So the answer is, no. You should start a new game whenever installing STEP for the first time. Once STEP is installed and a new game created, updating mods or to newer versions of the Guide typically does not require a new game.

[Greg]

The primary issues are that existing saves may have mods or other settings baked into the save that can conflict with the new load order. There are also a lot of mods in STEP Core and Extended that need to run scripts to configure themselves (like all the MCM settings) or that have trigger points that need to run. You'll probably be OK using a pure vanilla save that's saved right after you leave Helgen, but I generally use and recommend Alternate Start to start a new game. This way you can safely start just about anywhere in Skyrim without having to go through the cart ride again.