Same thing here! Got a honda 4-5 years back and it's never been out of the box. Art says its just fine as long as you haven't fueled it up. The innerds are coated in something when it's manufactured allowing it to sit safely on the shell until it's sold.. Ours just sits longer than most.

Once it's had fuel in it;

Use a Fuel Stabilizer, but make sure it's suitable for Ethanol blended gas (ethanol vs alcohol based stabilizer) as most now have it

And if it's stored where it's exposed to fluctuating temperatures, it's a good idea to give it an annual run to warm up the motor then an oil change to remove moisture from the crankcase

Another thing that needs to be considered is your electrical cord size.

I killed a similar cheap generator a few years back by pulling full load on a 50 ft 16/3 cord. The line losses pushed the generator over capacity and blew something up inside.
Cost as much to fix as to replace.

If your going to be pulling 3/4 capacity make sure you have a 14 or better yet a 12 gauge cord.

Once it's got gas in it just store it with fuel stabilizer in the gas and your good to go. If you store it outdoors it's a good idea to fire it up every month or so in the colder times of the year.
I too had one sitting in the box for a couple years before it got used, that's a great buy at Canadian tire for the Champion generator I have the same except one step up and good for 3000 watts with the 4 outlets so I can run some house lights etc. as well as my tanks. And yes make sure your extension cords are minimum 14 gauge or 12 gauge even better.