>>52706417>Vaporeon/Jolteon/FlareonRandom whilst you don't fulfil any of the following conditions:
>Espeon/UmbreonWalk as your buddy for 10 KM and then go evolve during the day or the night respectively.
>Glaceon/LeafeonInteract with a Poké Stop that has a Glacial Lure or Mossy Lure active, doesn't need to be your buddy.
>SylveonEarn 70 hearts with Eevee set as your buddy.
When your Eevee is eligible for a non-random evolution, the "?" icon will be replaced with a silhouette of what it will evolve into.
As the other anon said, the naming trick exists, but you can only perform this once per account. Don't waste this, it's very useful for Flareon, Jolteon, and Vaporeon when you get something with an ideal IV spread for PvP, and lets you shortcut a lot of prep-time for Sylveon, Espeon, Umbreon, as well as bypass the need for a lure module.
I recommend you wait on evolving Eevee until you reach level 41, as one of the requirements for reaching level 42 is to evolve all 8 different eeveelutions. The game doesn't give you a clear indicator of what remaining eeveelutions are needed, either. You just need to remember or keep track.