Mauricio Pellegrino oversaw the first of his training sessions on the pre-season camp to Austria then stressed the importance of the next few weeks for him and his team.
Saints flew out on Monday for their first trip of the summer, getting straight to work on arrival.
They will continue to train throughout the week, largely taking part in double sessions, before facing St Gallen in their opening friendly of the summer, on Saturday.
With another training camp to France to follow later in the month, Pellegrino says the coming weeks are crucial.
"Today was our first day together, because on Friday we received ten players [back from international duty] more or less, and we are waiting for the third group to receive another five,” he said.
"Every single day is important for us, because in these six weeks for us we have to create one style of playing, one model, one behaviour, an understanding between the players and the manager, between medical staff and us, and not just inside the pitch but also outside the pitch.
“We have to meet how they are, because you know that in modern football today there is a lot of diversity. We are a lot of people with different behaviours, different beliefs and we have to try to unify all the things, to create one team on the pitch.”