Defenately teach one command at the time. If you ll teach few commands at a time it might confuse the pup. I started to teach Maxi since I got him at two and a half months old. Now he knows most of commands
Its always great to teach them right away. Once you ll master one command start working on the other. Once your pup gets the other command make the baby do two commands and then give a treat. Worked for me, now Maxi does all commands for one treat