At that age (days old), they really need to be kept away from heights, though a fall or two likely won't hurt them. Once they're more steady on their feet and moving around without the clumsiness of young chicks, then I'd consider introducing them to the ramp.
When we have chicks that hatch under a momma hen, they go to our ICU coop, which has an upper level with nesting boxes, a roost bar, a door to the "downstairs", and a way to close that same door to the lower level.
For the first week or so, we'll keep that door closed with the chicks and momma hen confined to the upstairs with food and water. Only during supervised "outside" time do the chicks come out with momma hen, and we bring them out by hand; we don't let them try to navigate the stairs down..
Once they're starting to show signs of strength and agility, somewhere toward the end of the first week and into the second week, we'll start teaching the chicks about the stairs to the upper portion, but we teach them to go up first, so they know where they're going. They'll also watch momma go up the stairs too, and they learn quickly. Once they've learned to go up, coming down is easy.