Before making your winery reservation it is important to decide on the wine region you are going to. Then select wineries available in your chosen wine region and make reservations at desired times.
Here are some resources on helping you select a wine region:
Pessac-Léognan Wineries Open to the Public
I do not recommend driving to wineries if you do not have confirmed appointments there. Bordeaux châteaux often have limited staff onsite, so when you arrive, there is a chance the door won’t be answered.
It is also important to time your appointments and movements well. Consider visit times and distances between various wineries and give yourself extra time to stop for an occasional photo, coffee or even to find a château entrance. Wine tours may get cancelled if you are more than 10 minutes late.
If you need help putting together your timed itinerary, please check out my Bordeaux Wine Tour Planning Service. I will make reservations for you and deliver a custom timed itinerary including your favourite wineries and other grand cru classé wineries available on your date.
To plan a self-guided tour in the Médoc, you may find my Médoc Tour Guide useful.