How long does it take to activate my account and my card?

For the Classic Nickel card

You can use your account and your card as soon as you've collected your card at a Nickel Point.
Your secret card code is sent to you free of charge and immediately by SMS to the phone number you registered when you opened your account.
 

For personalized cards: My Nickel, Nickel Premium, Nickel Metal 

Upon receipt of your card, you can activate it directly on your Customer Area online or Nickel application. If you ever had a Classic Nickel card, it remains active until your new card is activated.