How long can I drive on a Donut (spare tire)?

Well here's the situation. I got a flat yesterday morning on my way to work, I do deliveries (yes with 'my' car) and I had a brand-new spare tire in the trunk (2008 Honda Civic) which was never used til' now.
The thing is, I have tire insurance through my monthly payment arrangements with Honda. I call the claims department, and they said to take the car to a Honda dealership and to call them back to confirm replacement. So I call Honda (where I bought my car) and made an appointment for first thing tomorrow morning (Saturday), to replace the tire.
This was on Friday morning, before I was going to work.
I went to work on a donut spare, and I had to do deliveries (about 40 miles worth of driving) and I was nervous about driving around on a donut too long, so I kept my car under 35 mph for every delivery.
So anyways, next day comes, (Saturday morning) and I called Honda to confirm I'm coming in, then I called the Insurance department, and they were freakin' closed! They're only open Mon-Fri.
So now I can't call them to confirm replacement by the dealership! So I cancelled the appointment, and made it for early Monday morning. But the problem is, I have work tomorrow (Sunday) again, I usually don't get as much deliveries as I did on Friday, but my car is 'still' on the Donut.
I refuse to buy another tire, because I've been paying for this damn insurance for 3 years (additional 10 dollars monthly) for situations like this, and now they're not even available when I need at the moment. So I'm not taking money out of 'my' pocket for something I've 'already' been paying for 3 years. So will I be ok to take this car to work for one more day? Is it safe, even driving safely, and driving the car under a safe speed limit? I'm just furious right now with the claims department, I told them I made an appointment for Honda next day, and they didn't bother telling me they are closed that day. So I'm stuck here. I looked around even for a used tire, and I can't find nothing less than $50, and I don't want to buy anything for this damn car if I have insurance I've been paying for.
So far $10 monthly, for 3 years is $360! And this is ONE tire. I'm gonna pay money out of my pocket for another tire (probably $100) while this insurance walks away with my money?
Does anybody have suggestions? Or have had similar situation or knows anything of what I can do with the insurance company maybe? And I will my donut make it tomorrow for work?
please help.

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