His side came out in Group G in Friday's draw ceremony at the Kremlin State Palace in Moscow, along with Belgium, Tunisia and debutants Panama.
England will open up against Tunisia on June 18.
"The interesting thing for us is starting later and what that might mean for us at the end of the season", he said.
Belgium are 10 places ahead of England in the world rankings, but both teams went unbeaten through qualifying and their encounter on paper is one of the ties of the group stage.
"We have got to get that period of recovery and freshness right".
Nobody in England will underestimate a Belgian side full of Premier League stars such as Kevin De Bruyne, Eden Hazard and Romelu Lukaku, but there will be confidence that they can finish in the top two.
England will have no excuses should they fail to qualify from their group at next summer's World Cup after Friday's draw, former worldwide Danny Murphy told The Debate.
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When asked about England's chances of winning the tournament, World Cup victor Gordon Banks said: "If they start straightaway, getting some results, playing pretty well, then they'll stand a chance".
That could be seen as a match to decide the victor of the group, but, with England having finished second in a group containing USA, Slovenia and Algeria in 2010, before failing to get out of a group also boasting Italy, Uruguay and Costa Rica in 2014, Southgate feels a team that lost to Iceland in last 16 of the European Championship past year can ill-afford to look beyond any opponent.
"I go back to the last two tournaments".
"Gareth someone I know well and we have shared big tournaments together covering the Poland and Ukraine Euros".
"About a 50 per cent chance we get England", Vertonghen says, before admitting: "I don't want to [get them]".
Southgate believes Belgium - managed by Roberto Martinez with Englishman Graeme Jones as his assistant - are among the favourites to win the trophy. They have talented players.
"They are clearly favourites from what we have seen in recent years, with the coach they have, and then second place I honestly think will be between England and us".