Linear Regression on Time Series

[karlito]

The error is clear - string '2017-11-10' could not be converted to float (obviously)

Yes I can read :) but for regression purpose, I read that all dates should be passed through pandas 'to_datetime()' function to convert it to float numeric because corresponding dates will be saved in the 'x' variable.
nb: before setting Date_Time as index it was already converted to 'to_datetime()'. I'm kind of lost. Any ideas?