I think the opening delay is not really that important, it will average out over the tank and with the calibration value. But if you are going for that absolute precision over say like 1000 miles it might throw the numbers off a percent or two
I don't think it is worth adding it now. But when coding it may be good to keep in mind that it might be added in later. So that could help keep from making changes that would make it really difficult to add this feature in the future.