At that young age I would focus more on training loose leash walking than using management....nothing wrong with using either if needed but the goal should be walking with you regardless of what he is wearing. It is easier to train it now while he is still relatively small than waiting til he is really big.
Everytime he starts to pull stops and dont move til there is slack in the leash again or do a complete 180 and briskly walk in the other direction. Make sure you are giving lots of treats and praise while he is in position and maintaining it.
Yes, some walks may be just in front of your house, or up and down your driveway, and thats ok. Its a slow process sometimes
Also, I am not positive about mastiffs, but would assume its the same as danes (and there is a good chance you already know this) you want to be very limited on your walks, very short periods of time at this young age.