Because of ebay algorithms it can take a few days for your items to be shown properly in search again. I set up a store on a new ID this month and it took 5 days for my first sale, and then I got 6 sales in two days.

The way stores work you have paid for the month anyway, so try it out for this month, see if the sales pick up, and if not, you can drop it back the day before your re-billing next month. In my experience it's unlikely a store would hurt your sales in any way, it just might not be worth the fee for some sellers.