The Three Lions kick off their group in Russia with a clash against Tunisia on June 18.
Southgate has to finalise his 23-man squad a fortnight before that Volgograd clash, meaning in theory those hoping to make the cut have one last chance to impress in the Wembley friendly against Nigeria on the first Saturday of June.
The reality, however, is that Southgate –who has to submit a provisional 35-man party to FIFA by May 14 – wants the make-up of his squad sorted long before that final deadline.
“I would like to (name the squad before the Nigeria friendly) because you end up being able to run a performance camp rather than a selection camp,” he said.
“There is a difference in the feel for everyone. If you name 28, they aren’t sure. But if you name 23 and five on standby – which Sven (Goran Eriksson) did well – then everyone knows where they stand.
“Those on standby have a chance but they come into the camp knowing their role. If you have 28 or 30 who think they might have a chance then there is a lot of uncertainty and anxiety during the games.
“For me, it is much better to have the 23 secured and go from there.”
Southgate was a player in 1998 when Glenn Hoddle chose to leave naming his final World Cup squad until after a trip to La Manga that followed May friendlies against Morocco and Belgium in Casablanca.
Eight players were cut, including famously Paul Gascoigne who smashed up Hoddle’s hotel room after hearing of his omission.
Asked if he had thought about how those who miss out this summer will be told, Southgate replied: “Yes, it is very important. But already, across this week, guys would have a good idea of where they sit.
“It is about managing expectations.
“There are some that have worked with us for quite a while and know the reality is they will be part of the squad. There are others that know after the conversations I have had with them that they are just on the edge of it.
“I think that is important because it doesn’t come as a huge surprise to anyone. I have got to keep those conversations going over the next few weeks.
“Letting people know how I see it so, in the end, it doesn’t come as dramatically to people.
“For any player (to miss out) is a huge disappointment. I guess it depends on how much they have been involved with us at that point.
“Some of the guys are coming in for their first couple of games so for them the scenario is different. I am sensitive to all of that so I have to deal with it in the best way possible.
“As a manager you have to have difficult conversations with people, but it is delivering that as respectfully as possible. It is never enjoyable for either person.”
Jesse Lingard was among those to have made a strong case in this week’s friendly double-header for not just making the plane to Russia but also starting against Tunisia.
This could be bad news for Dele Alli, whose only time on the pitch against Holland and Italy came via a late cameo in last Friday’s 1-0 win in Amsterdam.
With Lingard and Raheem Sterling linking up in such impressive fashion at Wembley, Alli could be forgiven for being anxious about his own prospects.
Southgate, however, is adamant that the Spurs midfielder is still very much in his plans.
“We want competition for places, but there is no ulterior motive to leaving him out,” added the Three Lions chief.
“Dele is a very important player but he wasn’t able to finish every session this week and we had to manage the problem he had when he came into the camp.”