Advise on pulling out equity!

[Eduardo Santana]

I recently purchased a property well under market value from a seller who wishes to stay in place for a year and then purchase the property back from me at market value. I received the initial appraisal and I was advised that the purchase was well under market value. I'm wondering if it makes sense to pull the equity out now and purchase another property or wait till I sell it back to the owner? Please if you can provide me with any advice that'd be great. Let me know if you need any additional information. Thanks!