Index series, shoul I read em from start?

[Otamegane]

After finally getting hyped about it, I've decided to read this novel series, and I created this thread for the purpose of asking some questions regarding it:

Should I start reading from volume 12 of the LN series to refresh myself and continue on, or should I go from the beginning reading every single one of the novels until the end of em?

If so, why? I know adaptions can be quite distorted from the original material, but is it really that different?

 

Also please do correct my English if possible