Generally I like to avoid all turkey calls before season starts just because you never know when your calling will attract a turkey and then, in turn spook it.

I don't think for a second if you gobble a couple times to try to locate a bird on the roost that it will "mess him up" before the season. I just have plenty respond to owling on the roost and crow calls as well.

As for a gobble, it may not be the case often, but if you have a subordinate tom or two that has been whipped, it may make them avoid the area if they think a boss bird is in there.

If your turkeys are like mine, likely they will gobble on their own anyhow, especially in the mornings. Then you can make them gobble at owls, and crows, why gobble at them?