When do I need to withdraw my excess 2018 HSA contribution to avoid any late fees or penalties if I am considering filing for extension? Would that be by Apr 15th or Oct?

I started my old job in sept. and left in December. In total, I contributed 1,054 dollars (which turbo tax says is all excess).

Because I have little time to withdraw (and my old HSA account info needs to be retrieved, customer service needs to be called, etc) I'm considering extending. 

But I'm not sure if this will actually fix my problem and allow me to withdraw earlier.

If I extended, would I then have until Oct 15th to withdraw the excess amount?