One point - don't be tempted by the old "put the new tyres on the front" dogma - the theory was that it was best to have the greatest amount of tread on the wheels doing the steering and the bulk of the braking.
These days, the current best practice is "news on the rear" as this improves grip in the wet - especially when turning corners - although it can increase braking distances in the wet :
Bazile - if you want to date your tyres you will find a 4-digit code on the tyre wall. It's easy to find and gives the date of manufacture as WWYY ie, 0118 is week 1 of 2018.