1 hour ago, chileheadmike said:All of the convection ovens I've used would bake conventionally.
Not my experience. My current kitchen has an electric convection oven with no options for the fan, other convection ovens have had the option of high or low fan. Commercial baking ovens are different from the home ovens with the option of convection.
Unfortunately I think you’ll just need to do some test baking to get used to your rental ovens. Start with just a few cookies till you’re happy, then do a full sheet and see if it needs adjusting. Mike is right in that no oven bakes perfectly evenly. Top rack may be hotter, or the back corner, etc. Always rotate!
Will you be able to get a better deal on space as you use more hours? If you’re already worried about test batches eating up the profit, maybe you need to charge more. Or make a 5 oz cookie, that’s still huge!