What is the right time to book the cheapest air ticket?

These are two ways of preparing your trip have advantages and disadvantages. So I will list your advantages and disadvantages so that you can choose the one that suits you best.
At the last minute

First of all by traveling at the last minute you can see several possible cases. Agencies want to do the figure, so at the last minute you can see broken prices for a flight that is normally worth double. So it's a good opportunity.

For hotels, it's the same. Sometimes, if you ask for a room the same day you can have very advantageous prices. I give you an example. I wanted to get a 4 star hotel room with my partner a short time ago right next to the champs. We took this room the same day and we got it in the neighborhood of the 130 euros although it was worth it triple. So there are benefits to be gained as late as possible.

You can unfortunately have disadvantages with this type of booking. Indeed, it is enough that there is more room in the hotel that you want or in the plane that you want or that you can not find yourself next to your family, it is all A stay that starts badly.

In this case we think, most of the time that it would have been better to organize the trip much earlier.

In the first minute

By organizing your trip in the first minute you can be sure to find a place on the plane you want and you can better choose your hotel because you already have a little more time before your trip. This allows you to set a date with the chosen flight and organize your stay, ie, visits to museums, monuments and other things to do in the place you have chosen.

The disadvantages of this type of trip is that you will not always have so many promotions. You can find some, but they are quite rare and you have to look. You will therefore pay more for your airline tickets and your hotel than a person who organizes his stay at the last minute in the same place as you.

The good choice

It depends on your expectations during a trip. 

If you want to make as many profits as possible, it may be better to do it at the last minute for accommodation and airplane at the risk of not having a place, or not being in a place you like. If you want everything to be perfect, have places to go to the places you want, have the accommodations you want and be sure to have a seat on the plane at the time you have decided Sometimes putting the price.