From what you describe, you may have 2 or more years before you take title (ownership) of the unit. You can only sell a condominium that you hold title on. You *might* be able to sell the agreement to purchase a condominium, the contract you signed but that depends primarily upon the contents of that agreement and often the mood of the developer.
The developer will typically, even with an assignment clause, have a number of restrictions on the sale including the ability to reject your buyer for any arbitrary reason. At very least there will be a number of fees charged by the developer for various bits of paper work.
The restrictions of the sale will be specific to your agreement. I strongly suggest you speak to your lawyer to help you interpret your agreement for restrictions and fees followed by the developer to see what their mood is (how flexible they are on those restrictions) before contacting a Realtor, and I give this advice as a Realtor.
Assignment of a contract is very very different than selling a condominium. You're selling a "condominium future", not a property. There are a lots of ways you could get into trouble that don't exist for typical sales of title.
For your own protection, please be darn sure to deal with a lawyer and Realtor who have experience in selling agreements to purchase.
Really, if the developer isn't happy with your buyer and they cannot unload the property onto someone else due to a down market then you might find yourself in a legal battle a few years down the line.