I own a small software development business. We charge customers maintenance fees on their software for 12 monthly installments. Should we enter a journal for each month, spreading the revenue evenly across the year, or should we enter the journal in the month it starts from? Our sales people get paid commission for the total invoice when it is sent. Any help for how to account for this situation would be appreciated.

thanks

The revenue should be recorded when the invoice is issued.
Issuing the invoice should result in a debit to the customers account & a credit to your Maintenance Revenue.