This is a well known travelers destination as well as a local population attraction. I'm sure they start in the morning around 9-10 and go into the night for the stores . The restaurants are usually always open. All the hotels and motels will probably have the Grapevine pamphlets or you can look on the internet or call them on their info line.
Most of the tourist type places will be open, as well as the restauents.
Get quick answers from Grapevine Historic Main Street District staff and past visitors.