I have a 24" Bluestar range. I mentioned on a recent thread that I have a 20" x 16" cookie sheet that fits fine. And I bake bread etc. Yes, it still takes time to pre-heat, esp. if it's 500 or more degrees. I'm going to guess that it's approx. 25 minutes. The broiler gets hot in 2 minutes though. That's fast. I have no problem with the size of the oven. It's fairly large as you've discovered. The oven racks are 20" wide and 18" deep, and the width of the oven is wider than the rack, so you can use the entire rack and air will still circulate. The height of the oven interior is 15" from floor to ceiling ,and 12" from lower rack to ceiling. If you needed more height than that, you just remove the oven racks and take the side rack supports out and lay them on the oven floor- they become a lower rack that sets about an inch off the floor.

The confusion is in the word seasoning in this application. OK it's not a wok or a cast iron pan that needs to be properly seasoned but here's Bluestar's recommendation: This is from the BS web site..."Your ring grates, top grates and burner heads may darken over time with use. This is normal. TIP: To prevent your burners from darkening at an uneven rate, rotate the ring grate and top grates between more and less active burners. BURNER CLEANING Ring Grates and Top Grates TIP: Clean spills as soon as possible to prevent sticking and build up.  When burner is cool, remove the ring grate, top grate and center filler grate (30” models only).  Wash in hot, soapy water. Rinse well and dry thoroughly to prevent rusting.  Handle gently to prevent nicks/chips, which can lead to rusting TIP: If you have a nick or chip you can season the area to prevent rusting. Nicks or chips are not covered under warranty.  Put corn oil or other high smoke point oil on a paper towel and rub onto rusted area.  Wipe away excess oil and replace the part on the range. Do not submerge the burner grates in water for extended periods of time. Prolonged exposure to moisture may cause rusting.  For heavy soiling, use a commercially available oven cleaner. Follow the cleaner manufacturer’s instructions. Make sure the cleaning chemicals do not contact any stainless steel or painted surface on your appliance.  Reinstall grates in cooktop and make sure they are seated properly, and do not move unsteadily from side to side". So, BS says it's OK to hand wash or DW and they also use the word "season" so this is maybe why it's a bit confusing to some. It's not seasoning in the traditional sense but oil on these grates will keep them looking good over the life of the grates, IMHO. This isn't that different from keeping your backyard BBQ grates from rusting, same principle.... Here's a tutorial for cleaning, this is just informational.... cleaning your bluestar grates

I purchased two basic 30" Bluestar ranges on special sale, for $1750 each, for my sister and her best friend about a year ago. They do a lot of wok cooking, roasting, and very little baking. One is a DIY, the other less so, and yes, they've had to replace most of the igniters. They are also chefs, and accustomed to taking extra care with professional equipment. Verdict? You might as well take their right arms off at the elbow than get them to switch ranges! Foremost on their list of "pros" is flame and temperature control, specifically high heat wok cooking. Both claim professional results, as confirmed by many on this site. If you are crazy for Asian cuisine, you've found your mid-priced range. My sister, Ann, also loves the broiler, which gives her meats the sear she loves to put on her dinner table. They do not recommend any professional range to beginners, unless you are willing to go to cooking school, and I agree. I chose to go with a little Capital 24" range, which I hope to have up and running soon. I am more of a baker than a wok wizard, and not much of a housekeeper, so sealed burners (easy cleaning) and precise, even oven heat steered me towards Capital. The Bluestar's open burners are the secret to high output flame control, but they don't wipe clean the way sealed burners do. My sister says it's no problem at all, especially for her new best friend... Research shows the designers at Bluestar and Capital have historically produced commercial ranges only, making inroads into people's homes just for the last few years. The reverse can be said of residential brands such as Kitchenaid, Whirlpool, Thermador, etal. I think it's important to remember the difference, since form follows function in so many of our choices. Commercial ranges have less to do with stylish appearance than durability, high heat, and precise control, all of which comes with costly maintenance (including replacement parts and repairs), and of course, astronomical prices. That said, the Bluestar is a very stylish package that satisfies in both commercial, and residential, applications.

One thing you didn't say was whether your BS is gas or electric. They do make electric wall ovens. I am going to assume you have the gas range oven as it is more common. Not everything needs convection or should use convection. If you are baking, use the convection. Roasting, don't use convection. Gas ovens without convection produce superior results when roasting. If you are baking and need even heat throughout for cooking and browning, reduce the temperature by 25 degrees. If the recipe calls for cookies at 375, cook them on convection at 350. The times should be similar or a little less. You will have to test for doneness. It's a more manual method of baking. Now days, many electric ovens will do the temperature conversion calculation for you when you select convection mode. People have forgotten that they need to do this. With the BS gas, you will have to go old school and do the conversion in your head. One thing that you need to be aware of is the need for extra pre-heat time. It's really important that the oven be at full temperature. This takes time and it's a big oven to heat. So, give yourself a lot of time for pre-heat. That may be one of your difficulties, an oven that isn't at full heat. I would also get an oven thermometer and keep it in the oven. I never trust my ovens. I've cooked in too many different ones to trust them.