Basically with multiclassing that early it's all about your opportunity costs. Just ask yourself if having that shiny ability now is worth not getting your level 11,14 and 17 ability "on time". In my experience it's usually worth it. Currently I'm playing an archer, started as a fighter for con saves, proficiencies, and fighting style, then went 4 in rogue because he is going to be mostly arcane trickster(for the spell slots and versatility) at level 6(currently) I took a level in ranger as I plan on going level 5 in ranger for ensnaring strike(main cc spell) horde breaker, and extra attack. I did variant human and started with crossbow expert. I am feeling it a touch, our other archer has a better sneak attack than I do. But I hit twice as many times a turn and I have a +2 to hit so I connect more often. For me the question of delaying the big rewards of extra attack/uncanny dodge 3d6 sneak and asi's(I am feeling my 16 dex, darn my bad rolls) was well worth getting the starting bonuses in fighter and getting my spells earlier.
There isn't a right or wrong answer, just preference really :/
Indeed.
The opportunity cost is leessened when you stack features in the same area of expertise. Going Fighter2, then Rogue 4, then Ranger 5 will have you at Fighter 2/Rogue4/Ranger5 at level 11.
This gets you 2 fighting styles. 3d6 SA, Extra Attack and 3 caster levels. It functions but you'll feel the hit. The feat is what holds it together. A fighter 11 would have 3-4 shots a turn and a ranger 11 would have volley, 11 spell slots and know 3rd level spells.
So it really depends on how the campaign runs. Horde heavy, elite heavy, "solo" heavy, or a mix. Heavy combat, low combat, moderate combat. The reward of going to 11 is that these issue matter less.