The hose is a good method - just lay it out and move it until you like the shape. Don’t make tight radius bends.

If you are laying stone slabs in mortar, the curved edge will be annoying to lay out ... if you set them all and use a stone saw to cut slabs and mortar into the curve you will have a problem with the slab and stones breaking apart and chipping the edges.

Your best bet is to lay the patio dry, starting with the curved edge, making sure that any stones that are along the edge are as big as possible, with no small remnants at the edge. Work inward.

Then mark and cut the outer edges, and mark all the stones - number them or somehow make it possible for you to move stones, put mortar down and put stones back on mortar. If you have room, creating the patio somewhere else in your yard and moving stones from the dry run to the mortar bed would be the easiest way.