"Everything starts as somebody's daydream. And, when you're daydreaming, it is science fiction. It's when you start work out how you put it together, true science fiction becomes real science."
- Larry Niven

E.E. 'Doc' Smith uses the same term in Triplanetary (1934):

They came to a stop--paused, weightless--a vast door slid smoothly aside--they were drawn upward through an airlock and floated quietly in the air above a small, but brightly-lighted and orderly city of metallic buildings! Gently the Hyperion was lowered, to come to rest in the embracing arms of a regulation landing cradle.

Again in Hotel Cosmos (1938) by Raymond Z. Gallun:

“Space Liner Ardis coming in from Planet Five of Antares. Landing at 10:19 p.m. in fourth cradle of Civic Space Docks. 4-2-5 on board! 4-2-5 on board! Caution! Caution!

Poul Anderson liked it; he put it in The Corkscrew of Space (1956):

Laslos Magarac threaded past the crowds till he got to the spaceport fence. He had an impulse to pay a dollar to one of the telescope concessionaires for a look at the fifty great ships orbiting around the planet, but decided against it—the line was too long. After all, twice a local year was about once an Earth-year, so it was a capitalized Event—but the shuttle boats blasting down, sheeting flame through clouds of kicked-up red dust, were spectacular enough.

There was one arriving now, descending on a tail of fire some four miles away—which put it almost on the horizon. It was a bright gleam against the dark-blue sky, under the shrunken sun. As he watched, it entered its cradle...

Randall Garrett used a variant in Needler in 1957, with a nice illustration by Emsh:

The Killiver was sitting in its launching cradle at the far side of the ten-mile-square Grand Port of Kandoris. Roysland didn't bother to take the tubeway; he flashed his credentials and commandeered a surface jeep. Bilford had already taken charge of the crew, but Roysland wasn't worried about them; he wanted a look at the ship.

(Landing-Cradle from Needler by Randall Garrett)

A variation of the same expression, from They Never Came Back (1941) by Fritz Leiber:

HEY, YOU! What’s your business?”

Bart Harlan, standing on the cat-walk that circled the upper rim of the docking-cradle, did not immediately answer the shouted question. He clung to the thin hand rail, bracing himself against the sheets of rain which drove across the almost deserted landing field, and stared wearily down into the shadowy interior of the cradle...