Place the ham in a large slow cooker. Whisk the cider with the brown sugar, bourbon, honey, and mustard. Slowly pour over the ham. Scatter the thyme sprigs into the slow cooker.
Cook, on HIGH for 4 hours or on LOW for 8 hours, or until very tender. Remove ham to rest on a cutting board. Pass the remaining cooking liquid through a fine-mesh sieve into a saucepan. Simmer for 10 minutes or until slightly reduced.
Cut the ham into chunks or slices. Brush the cut pieces with the cooking liquid before arranging on a platter. Serve warm or room temperature.
*For a non-alcoholic alternative: replace the bourbon with 1/4 cup water and 1 tablespoon vanilla extract.