land contract - when to use a notary?

[Paul Tomlinson]

I am in the process of having a contract signed on a
property that I own via a land contract (land purchase contract). The document that I am using requests the
authenticity of signatures through a notary. At what point
does the notary become involved and on who's end?
I (the seller) and the buyer live in two different states.
Am I right to wait for the signature of the buyer before
I sign (and get it notarized on my end) or do I sign, have
the buyer sign, and have the document notarized on the buyers end?