Welcome aboard~ Hope this helps.
First, you want to crate train the pup. Make sure you have a blanket, stuffed animal (about their size) and white noise (ticking clock or ipod with soft music) so the pup can sleep. The pup is used to cuddling with siblings.
Second: you want to keep the pup in a room with a family member. Mastiffs need to be near their family members.
Third: you want to start the pup’s food regimen. Are you feeding them what the breeder fed them? If yes, ok. If not, you need to do a slow transition to the new food. Mastiffs are allergic to chicken and grain in kibble. Slow transition is to feed 1/4 of new food with 3/4's of old food for 3-4 days. Transition to 1/2 new and 1/2 old food for 3-4 days. Transition to 3/4 new and 1/4 old for 3-4 days. Transition to 100% new food. If at anytime the pup has diarrhea, return to former transition amounts until diarrhea stops.
Osteochondrosis: An Orthopedic Disease in Large Dog Breeds
Fourth: You want to keep the leash on the pup for a few hours each day while in the house so they gets used to it.
Fifth: Keep the pup away from dog areas unless they have had their 2nd set of shots leaving the pup prone to getting parvo or other illnesses. Keep the pup in your yard and place newspapers down where they will walk on the ground. This is very important!
Sixth: Start basic commands. Train for about 5 minutes per day and slowy increase the training time. Teach one command at a time. Once they master one command, move onto another command.
Mastiffs can be extremely stubborn and if you get frustrated with them, they will shut down. Mastiffs do not do well with yelling or hitting. Hitting can result in some unwanted mastiff behavior meaning fear aggression, which equals biting.
Number one command is sit. Teach the pup to sit, by placing a treat in front of his head and move it to the back causing him to sit to get the treat. When the pup sits, tell them good sit and give them the treat.
Second command should be "focus/look" This will help you tremendously when the pup is over 100 lbs. Put the pup into sit. With a treat in your hand (let the pup smell it), put the treat up to your eyes and tell the pup to look or focus. They may only do this for about 1-2 seconds. As soon as they look at your eyes, tell them good look or good focus and give the treat. Some mastiffs (DDBs generally) do not like to look anyone in the eyes for long because that means a challenge to them. Titan is up to 35 seconds of looking at me.
Other commands to teach is stay, come, leave it and drop it.
When you are training and when the pup does not do as you ask, then tell him no no no and redirect back to command in a normal voice. The only time a stern and somewhat loud NO should be used is when they are doing something that can cause harm to themselves or others.
For example, when I'm doing the look at me training with Titan. He will look at me and then his eyes will move to the left or right. I say, "no no no, look at me" and he returns to the look to my eyes.
When they do what you want them to do, get all giddy and excited and say, "Yes, good look!" I clap, giggle, and sometimes do a little dance. My dog looks at me like, really woman?
Puppies should not do any heavy exercise or walking for the first 1-2 years. Stairs should be maneuvered while on leash (even in the house) especially going down the stairs. Stairs should have carpet or rubber matting to give the pup traction. Most mastiffs (DDBs especially) can be very lazy but they still need to exercise. Puppies should not be walked for more than 15-20 minutes for the first 6-8 months and do your best to avoid heavy running or jumping for the first 1-2 years. Excessive jumping, running and long walks (1-2 hours) can cause hip, elbow, knee and joint injuries.
Remember, mastiffs do not tolerate heat. In the heat, reduce walk/exercise times. Have clean water available at all times. I freeze towels to either place on Titan or put on the floor for him to lie on in the summer to cool him off. Buy a kiddies’ pool for the pup to play in to keep cool.
Mastiffs should not be neutered/spayed until 18 months to 2 years. NO MATTER what the vet says. Early neutering can cause growth problems.
Enjoy your baby! Have lots of patience! The pup will reward you with love and loyalty!
