Can I ready an action before combat, and then use it immediately after, or just before combat starts? [duplicate]

Question

I'm aware that you can use an action in combat in order to ready a specific response to be performed as a reaction when a certain event triggers it.

But what if I'm in a situation where combat hasn't begun, and want to ready an action?

Take this situation for example

1. I approach bandits in a tavern (No combat yet)

2. I confront them and sense that things are about to get violent

3. So I ready a firebolt spell (Before Initiative Rolls) and set it to trigger as my reaction when I see one of them draw their weapon

But since combat hasn't started yet, and I'm in no position to ambush, can I get a head start by readying an action before SHTF.

And if so can I set it to trigger as a reaction to them drawing their swords to begin combat, and fire at one of the bandits before they can react

What happens? Does it count as some sort of opportunity attack, or does it trigger as an bonus/extra attack/reaction/action on my first turn. or is it something else entirely?

In other words, do I have to be in combat in order to take the "ready" action, or can I do so before initiative has been rolled and still gain its benefits.

If I can take the action it before initiative is rolled, does my readied action trigger immediately after the bandit draws his weapon (as described above) or what?

Answer 1

The only rules on readying an action are found in the PHB page 193 and say that you have until the start of your next turn to use a readied action. A turn is 6 seconds. However, I don't realy think that's what you want in the scenario you talk about. Because when you ready a spell during combat, you use your action to cast the spell but hold the actual release. That means full use of verbal, somantic and material components. The bandits in the tavern would clearly see you casting the spell and would probably not be too happy. I would step away from the combat rules and just treat it as an RP-scene. Tell the DM "I pay close attention to the bandits and will cast a firebolt if they try anything.". That can be solved by the DM in many different ways - one of which is to let you cast the spell before rolling initiative.

I think the "problem" here is that readying an action is a combat rule, and you're not describing a combat situation. The rules still apply, but might not be the best way to bring what you envision into the game.