In 1., 'earlier', notice the -ed, functions as a comparative, like this,Originally Posted by jack
I left my house 30 minutes earlier than usual, so I wouldn't be late.
In 2., 'early' modified the verb 'left'.
In 4., 'won't' is a contraction of 'will not'. The problem with 4. is that 'will' refers to the future, whereas 'left' refers to the past. Both verbs should be in the past or in the future, like this,Originally Posted by jack
I left..., so I would not.... (Past) :D
I will leave..., so I will not.... (Future) :D