When should I initiate Prison/Bozak/Following quests?

[Netsa]

When is a good time to do these? I've been avoiding them since I thought they were endgame content, but I don't really know. I'm level 20 now, but should I wait until I've completed the story? Or am I supposed to do them before the end of the story?

[Blade Master]

These are indeed end game content, however if you play with experienced players who can help / carry you through, you can really do it anytime. For solo:

Bozak Horde - do it when you have maxed out in Power and Agility skill-trees, even better if you have several Legend skill-tree ranks. There is full detailed guide about Bozak Horde at my profile.

Prison Heist - do this when you have maxed out in all base skill-trees and obtained at least 2-3k damage gear, for Normal mode. For Hard mode especially NG+, you'll want to have perhaps few dozen Legend skill-tree ranks. For Nightmare NG+, bring several dozen Legend skill-tree ranks. You'll want to bring resistance boosters, flares and cloak potions in Prison Heist in order to maximize your speed.

Bozak Horde and Prison Heist are unrelated to story and can be done, as well as repeated anytime and farmed for Gold-tier weapons. More info about Gold-tier weapons at https://dyinglight.wikia.com/wiki/Gold-tier_Weapons.

As of The Following, this is story continuation of Dying Light, so you can feel free to start it whenever you finish campaign. I'd suggest making sure you finished everything in campaign before you start The Following. The Following is step into a great journey, have fun.

[costas]

Here is a guide on Prison Heist: https://steamcommunity.com/sharedfiles/filedetails/?id=1423108742