How long before I should contact a local bank about refinancing?

[Derek Ferguson]

I just closed on a 4 bed 1.5 bath in Roanoke, Va. The purchase price was 61k and I put 25% down. I got the loan through a local credit union. My payment including taxes and insurance is $397 per month and I believe I can rent this property for $900 per month after renovations. I expect the renovations to cost about $15k. It appraised for $78k in it's current condition.

My question is how long should I wait before contacting a local bank about refinancing the property? Should I wait until I have it rented for 1 year? If anyone has experience with any local banks in Roanoke and knows what they expect I would love to hear about it. Thanks!!