Auto creation of Opportunity Number

Auto creation of Opportunity Number

I am looking to create a field in which I can create a auto number for New Opportunities.
When a new opportunity is created I would like the number to be created in the following manner.

YYMM###-NN
YY -the last two digits of the current year ##
MM -the current month digits ##
### -an autonumber starting at zero that restarts each month ###
NN -Nick Name of the current user.

Could anyone help me with a formula or combination of fields that would create this for me.