1031 Exchange: How long do you have to rent?

[Macy Bassler]

For an investment property to qualify for a 1031 exchange, is there an established minimum that you have to have a tenant in the house before you sell the home and exchange for the next investment property? For instance can you rent it out for 6 months and then do a 1031 or is that illegal/toeing the line of being primarily a flip (if you had in some way artificially appreciated property) and therefore not qualifying for the 1031 exchange?