Have your sidewalls actually cracked or do they look OK?
Unless they are cracked I would use them until the new ones came in. Just don't overload them and maintain the proper pressure for the weight. Michelin reported 200 failures out of 150,000,000 tires. Thats like less than .000001% I doubt any other brands are any better. Of course Michelin would say don't use them just to protect their backside.
I've ordered mine to replace my four year old set but I will not to worry and not use them until the new ones come in. After all, they've been fine for four years, I don't think a few weeks will make any difference.
2006 Fleetwood 26Q
2010 Harley Softail Toad
2015 Ford Focus Toad
Upstate (the other) New York