If you are purchasing a property to renovate and the list for sale again, you should wait at least 90 days (from the date you closed on the purchase) to put the property back on the market. 

If you only waited 30 days to put the property back on the market (kudos to you for a speedy renovation job) and if a buyer then comes along and writes a contract on the property before 90 days have passed, then the transaction will be flagged as a flip via the appraisal property.

Once flagged as a flip, by Fannie Mae / Freddie Mac guidelines, there will be a variety of implications for the transaction:

• two appraisals will likely be needed, instead of just one
• the appraiser will likely need a list of the improvements that were performed along with the value of each improvement
• purchasers (borrowers) will be required to have at least a 20% down payment

The third item above (20% down payment requirement) is what can quickly make a deal backfire, especially if you have purchased and renovated a home that will be appealing to first time buyers.....many of whom will not have a 20% down payment available.

So, as an investor, or someone considering purchasing a property to renovate and then list for sale, it is highly advisable that you wait to list the renovated property for sale until at least 90 days after you closed on the purchase of the property.