Of American-English origin, the noun staycation is a blend of stay and vacation and denotes a holiday spent at home or in one’s country of residence.

The earliest occurrences of staycation that I have found are as follows, in chronological order:

1-: From Stay at Home and Have Fun – – – Here’s How, Explains Snaffie, published in The Cincinnati Post (Cincinnati, Ohio) of Wednesday 28^th June 1944:

Patriotically observing travel priorities and gasoline rationing and undaunted by the heat, J. Snafflebit-Saddlecloth, peacetime world traveler, proceeded Wednesday with stay-at-home vacation plans. […]
Any Cincinnatian can spend funful days at minimum cost at City Recreation Commission playspots within easy reach by the city transportation system, then, like “Snaffie,” wind up with a refreshing dip at Coney Island or one of the many city pools.
Or, if the stay-at-homer is a disciple of Izaak Walton, like the versatile “Snaffie,” there are many spots along the Ohio River where he can pursue the finny fellows that lurk in the deep pools. The Chamber of Commerce has a stay-cation chart and the Recreation Commission will guide you.

2-: From an advertisement for Felsenbrau Supreme Beer, published in The Cincinnati Enquirer (Cincinnati, Ohio) of Tuesday 18^th July 1944:

FOUR RED-WHITE-AND-BLUE REMINDERS FOR JULY
1. Don’t let the hot sun cool off your enthusiasm in your Victory Garden. It’s what you harvest, not what you plant, that’s important.
2. Take a Stay-cation instead of a Va-cation, this year. Trains and busses [sic] are crowded. Gasoline and tires must still be conserved.
3. Fill your coal bin now. Neither the mines, the railroads nor your coal dealer will be able to handle a last-minute rush.
4. Remember, no soldier ever got too many letters. Write every week. Write today. And send it V-mail [cf. footnote]. It’s safer, faster, surer. Saves vital cargo space.

3-: From a letter published in the Baptist and Reflector (Nashville, Tennessee) of Thursday 24^th June 1965—however, here, to take a staycation is used in a restricted sense, i.e., to stay at home, in summer, with visiting relatives or friends, instead of attending church:

. . . Ever Heard of a “Staycation”
● The work of Christ suffers during the summer months because some church members are away on vacation. But I have a feeling that church attendance is down more because we take a “staycation” from the Lord’s work during the summer.
Friends and relatives come to visit. We are proud of our town and the surrounding countryside. We waste no time showing off our wonderful community, parks, fishing spots, and recreation areas. But when Sunday comes, we just stay at home with them.
“We didn’t bring any Sunday clothes,” is the stock reason that seems to excuse them and us from attending the services of our church. Our company often leaves right after the big Sunday meal at noon. For some strange reason, we feel justified in staying home from church to fix the noon meal and bid farewell to our friends.
Thank the Lord for vacations when we can get away for a while and be refreshed! But may the Lord deliver us from taking a “staycation”!
Here’s what can be done:
1. When you invite friends and relatives this summer, invite them to attend your church too; encourage them to bring their “Sunday clothes.”
2. Don’t let Sunday feasting at home keep you from feasting on God’s Word at church.
3. When you are in town this summer, be present at your church.
Please don’t take a “staycation” from God’s work this summer.—Tal D. Bonham, pastor, South Side Baptist Church, Pine Bluff, Arkansas

Note: V-mail is the abbreviation of victory mail, a U.S. term which, during the Second World War, denoted letters to or from home, reproduced photographically to conserve shipping space—as explained in The New York Times (New York City, N.Y.) of Saturday 13^th June 1942:

Washington, June 12—The new V-Mail for United States overseas forces, patterned after the British microfilm postal system, was started when letters were delivered to President Roosevelt today from Ambassador John G. Winant and Major Gen. James E. Chaney, commanding officer of American forces in the United Kingdom.
[…]
General Chaney, in V-Mail letter No. 1, said the new service was “a distinct contribution toward victory since no other single factor ties in our soldiers with the people at home so much as prompt and adequate service.”
[…]
[…] V-Mail […] will involve the use of special note paper and microfilm apparatus.
The cargo space saved will be considerable. Twice to thirty-seven times as much V-Mail can be accommodated by one carrier as in the ordinary form.