Why don't you test each of these situations yourself & discover the balance point of influence for yourself?

You are using the word "Manifest" in a way that almost makes the phenomenon appear magical like the wave of a magician's wand.

First of all, this magical thing called "Manifesting" is not really that. It is an attraction, and it is the level of your own influence upon that attraction.

with reference to my first suggestion of testing it for yourself, you will find that the further away you are from the event, the more influence you will have in your favor.

So the example with the customer service queue, if you envision yourself having VIP treatment & jumping the queue ahead of everyone else weeks before the actual event, You will find that the universe has more room to adjust things in your favor & you may find an old friend behind the counter on that particular day to serve you.

The closer you are to the event the more you have participated in other scenarios of momentum where you have already agreed to participate in co-creating with and within other people's requests.

Mind you, what ever situation you find your self in, did not sneak up on you while you were innocently minding your own business bothering nobody.

If you have a life imprisonment sentence looming over your head, you either actively participated in getting your self there with much joy and enthusiasm, or you were always afraid of ending up in jail with a sentence of life in prison.
Either of those states of mind will produce the same outcome.

If you don't realize it by now, everything that you are afraid of happening to you will happen to you eventually as long as you maintain that focus within your consciousness.

So how does this magical "Manifesting" really work?

There is a magical component to this phenomenon that we don't need to get into for now. But if you are wondering, for that kind of control upon reality you need clarity of consciousness without any karmic loose ends.
You need to be enlightened for that kind of control. But then if you are, you wouldn't even use the word "control" to describe this influence upon reality.

The influence we exert upon reality in the form of the Law of attraction, is mostly the psychic influence we are exerting within the collective consciousness of all the participants within our reality.

Your Vision has other participants in it, playing the appropriate characters, just like in a play.

The clearer your vision of your intended reality the more influence your script has over everybody else's script running within their own consciousness.

But, then again, consciousness itself is a shared reality. We all dip into the same ocean of consciousness for inspiration.

So the further away you are from the event, the more the participants in your reality will appear to position themselves according to your script. The beautiful thing is that they will do it believing that they are actually following their own script instead.

If you get this, you will understand why all the media is controlled by a few powerful families and why they all show the same disastrous news.

disaster and war is where the profits are counted in dollars and the losses counted in lives (not my quote, it's borrowed)

The people at the top (they believe so) understand the collective consciousness phenomenon, and manipulate it to the fullest extent.

But you can take you control back by refusing to form your opinions from only the mainstream sources. You can choose what is supposed to happen to you.

The further away you are from the event, the more you will seemingly have and effect upon the outcome. And it is happening through the influence of the collective consciousness of the human mind.