If cooking right away, preheat the oven to either 375 convect or 400 regular.
Cut the lemon (s) in half or quarters and shove them into the cavity with the sprig or two of thyme. Then rub the outside of the chicken with olive oil and sprinkle liberally with salt and pepper. I happened to have a lavender pepper blend in my spice cabinet from Terraverde Farms so I sprinkled that on as well. Just salt and pepper will do. If you have lemon pepper, that would be nice as well. But don't over think it. Many spices would work but the basics will not disappoint if the chicken is cooked properly.
I have a convection option oven so I chose convection roast at 375 degrees and one hour was just the right amount of time. I'd probably go with 400 degrees in a regular oven and check it at one hour also. Doneness is determined in many ways - easy wiggling of the leg, thigh/leg juices running clear, internal temperature at breast or thigh of 165 degrees, nice browning of skin and juices running into pan and making noise while doing it.
If you're feeling really adventurous, after you take the chicken out of the oven and let it rest on the cutting board for 5 or 10 minutes loosely tented with foil, you can deglaze the pan on the stove top with some white wine, lemon juice and chicken broth - a great way to use up leftover wine or broth and a nice little instant gravy to put on your chicken.