I would also take a dip late if it might provide more utility than the final levels. I take it early when the abilities and extra class are part of the defining characteristics of the character.

If you are planning a dip, I tend to take it either early or late in the character progression. On the other hand, if you are a melee rogue wanting to use a shield and single handed weapon then you could take dueling or defensive fighting styles along with the shield proficiency so it becomes a bit more worthwhile. Getting the archery fighting style probably isn't worth it unless you want to for role playing/character background reasons. If you are ranged, the archery fighting style can be useful, however the weapon, shield and armor proficiencies are less useful. If you happen to be a melee rogue (and an elf/half-elf depending on the DM) then bladsinger wizard offers some decent additional abilities for a melee rogue. In your case, wizard 1 boosts your spell progression, adds cantrips and give you access to first level rituals. He has also taken sharpshooter to avoid cover and increase range, however, he can also use the -5/+10 for subsequent attacks after landing the sneak attack if it is worthwhile. the warlock levels have (in my case) added to the fun of the character in terms of roleplaying. I think the progression was something like rogue ->3, warlock-> 3, rogue->7, warlock->5 (for thirsting blade) and so far rogue->9. I have an arcane trickster/warlock multiclass that took 3 levels of warlock early for devils sight+darkness, blade pact and improved pact weapon so that they would have a ranged magical weapon for sneak attacks. However, depending on what you are looking for it can be worthwhile multiclassing. Rogues get some nice things through most of their progression.

It depends on what your goal is with multiclassing.

Rogue arcane trickster