Start investing with own house?

[Oswaldo Rodriguez]

Hello to all, I have a big question that I've been thinking for months now. Me and my dad are planning to start investing in a rental properties next year. We would like to start off by buying a single family home. We have some money saved but not enough for a down payment. My dad will finish paying his house next year and I wanted to know your opinions about him refinancing his house so we can start investing in real estate next year or just wait until he finishes paying the house and wait until we can save up more money to start investing? He currently has an interest rate of 6.5% on the house. 

I want to thank all in advance and any advice/opinion is greatly appreciated!