I see what you are getting at.
Assume you begin business -using your dates above- on Oct 5th. At the end of October you will not have the electric bill. So now you have two choices: Keep the books open for October until you do get the bill on Dec 10th -which has Oct and Nov costs - so then you must create an allocation for period from Oct 5 to Oct 31 out of the bill you get on Dec 10th.
OR - On Oct 31st estimate your electric costs and record an accrual.
Note that unless the Dec 10th bill shows daily usage, you will not accurately know your Oct (or Nov) electric costs. So, relax, estimate, accrue and move on to bigger issues.....