When is the right time for a couple to move in together?

There are no doubt obvious benefits like saving money and rent and living expenses but I'm wary of my boyfriend's suggestion that we move in together. I'm worried that it's too soon and will damage our relationship. We also live in an area where finding rental property is difficult and heaven forbid our relationship goes sour we'd be stuck in a lease together. I love him and we've been together for a year and a half. Do I just have cold feet or is there a proper amount of time to wait?