Must a monk's Flurry of Blows attacks occur after the initial (and extra) attack from the Attack action?

Question

Looking at the wording of Flurry of Blows, I may be overthinking it, but the description of the feature (PHB, p. 78) says:

Immediately after you take the Attack action on your turn, you can spend 1 ki point to make two unarmed strikes as a bonus action.

Does this imply that a 5th-level (or higher) monk must finish the Attack action (initial attack + extra attack) and only afterward can optionally use the Flurry of Blows bonus action immediately?

Or does "take" mean that a monk must start/commit to doing an Attack action, and before finishing the Attack action (or even make any attack rolls), they can initiate Flurry of Blows to make two more unarmed strikes? Can the Flurry of Blows attacks be before (or be interspersed in any order with) the two attacks from the Attack action?

Somewhat relevant is Mike Mearls' October 2014 tweet that movement can occur in-between/during Flurry of Blows attacks.

---

My thought is to gain the benefits of the Open Hand monk's knockdown ability tied to Flurry of Blows, and benefit from the prone status on the two attacks from the Attack action.

Example:

1. First Flurry of Blows attack; target fails Dex save and is knocked prone
2. First attack from the Attack action - target dies
3. Move to new target and use second Flurry of Blows attack; target fails Dex save and becomes prone
4. Second attack from the Attack action

(Alternatively using the Flurry benefits to remove reactions, etc.)

Answer 1

The rules on bonus actions say:

You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified

Here the timing is specified: "Immediately after you take the Attack action".

You must take the attack action which means, in practice, that you must make an attack using the Attack action (which you can substitute a trip or grapple etc. for) and then you can use your Flurry of Blows. To my mind, based on the ability to move between initial and extra attacks within an Attack action, you should be able to use your flurry anytime after that first attack i.e. before or after any extra attack.

So, you cannot use it the way you describe - you can, of course, substitute a trip for your initial attack if you want.

Answer 2

Based on Jeremy Crawford's tweet, going to answer this myself since the other answers aren't quite what he clarified:

1. start and complete the attack action ( 1 attack for level 1-4, or both from level 5+).
2. Immediately after the attack action completes, may use bonus action and spend ki point to flurry of blows.

I came back to this answer after reading the clarifying tweet about shield mastery, since now we have a consistent answer for both questions. So ready to resolve this one!

Answer 3

PHB page 192, Attack action:

With this action, you make one melee or ranged attack. See the “Making an attack” section for the rules that govern attacks. Certain features, such as the Extra Attack feature of the fighter, allow you to make more than one attack with this action.

We know that a character can move or use other actions between multiple attacks, so I'd say that you can take the Attack action on the start of your turn, and move or use other actions (such as Flurry of Blows) before the first or any other attack of your Attack action, allowing you to effectively use FoB before the Attack action.

Somewhat relevant and mentioned above, Jeremy Crawford confirmed in the Sage Advice that you can do the Shield Master shield bash before the Attack action. The wording in Shield Master is "if you take the Attack action on your turn (...)", and the explanation of how it's possible can be the same as the one I provided for FoB.

All in all, this seems to me as a bit roundabout way of doing this, and it may not be Rules as Intended, but I'd allow it, since the power boost doesn't seem that big.