That's very hard to say. Selling chicks/chickens is fickle and often a crap shoot.Do I set up an ad before or after they hatch?
If you(can) get people to commit, with money, beforehand they won't back out.
But if you don't get the hatch rate you think you will then you will have to reimburse.
If they don't have to put any money on the line you'll get a bunch of people who say they want them but many will back out.
Best to have the space and resources to care for the chicks in case they don't sell.
Keeping them until POL might be the best way to go, but it's more work and upfront cost.
Do you know the breed(s) you will hatch?
What is your real goal here?