We installed pavers on our 13 x 44 patio, and on the advice of a concrete contractor, first poured concrete, rather than laying them on grit which tends to settle. We just laid them on dry concrete, but glued down the perimeter row. Then we swept sand into the cracks to firm them up. We are very happy with the installation. We have had it 2 years now. I would recommend this method of installation to everyone. I don't think the cracks will matter unless they are uneven. And even then you could level it with sand before laying the pavers.