I'm a player rather than DM most of the time, but in our group multiclassing is almost unheard of before 6th level. However, some classes tend to be branched out from there. Ranger 5 happens, but then it's more common to have Ranger 5/other class 1 than having Ranger 6.
Rogue also often ends up with multiclassing around there, and sometimes fighter too. Other classes often have something on level 6 or 7 that makes us think "just one or two levels more".
There are times where a concept results in one level of a class to start (commonly something like fighter for hit points and proficiencies) and then the rest of the levels in a second class.
In short, it depends on classes and levels we're playing at. Also somewhat story.
Rogue also often ends up with multiclassing around there, and sometimes fighter too. Other classes often have something on level 6 or 7 that makes us think "just one or two levels more".
There are times where a concept results in one level of a class to start (commonly something like fighter for hit points and proficiencies) and then the rest of the levels in a second class.
In short, it depends on classes and levels we're playing at. Also somewhat story.