Facebook Ad Metrics

I have just started promoting my store but I don't know what to use as a traffic benchmark to see how effective it is. I have started a few weeks ago, had no sales, got one abandoned cart. I get around 50-100 views per day and around 10-15 users a day. I have not spent much money on facebook ads, if I dont make a sale after a day or two I stop them as I don' t know how to tell if they are being successful on other metrics. Is there a guide on what is realistic for new stores?