What's the "freshest" a note can be to be sold?

[Pat Jackson]

I'm becoming very interested in owner financing houses.  I've been reading a lot about wraparound mortgages.  Now I'm wondering if the wraparound mortgage can be avoided all together.  Here's my thought:

Do the first two steps of a BRRRR

Buy a distressed house

Rehab (with cash)

Then owner finance to a buyer.  Require a 15-20% downpayment.  Setup up a 15-30 year note.  

Collect payments

Sell note

My question is this:  How soon after I sell the house and collect payments till I can sell that note?  What what is a reasonable % on the dollar of the note?  Here's a numbers example (I'm buying in Missouri so the numbers are reasonable):

Purchase Price: 28k

Rehab and Holding: 25k

Owner finance for 85K @ 8% over 20 years.  Get a 15% down payment (12.75k), and have a 20 year note for 72.25k @ 8% (670.99 monthly payments).  

How long would I need the buyer to perform before I could sell the note?  What's a reasonable price for this note?