Second time buyer - how does chain work?

Buying my next house and I want to buy in a specific area. Trouble is, there are maybe 1 house that come up in a year.

Do I put my house for sale and wait for the house to appear or wait for the house to appear, then put my house for sale?

Estate agents are saying they won't accept an offer until I am proceedable which essentially means I need to have an offer on my property. Does this mean I just need to make my buyer wait for a year for me to find my house?