Short Answer 
To find out when a contact created their Telegram account, first open the Telegram app and log in. Then, navigate to the Contacts section, select the desired contact, and tap on their profile picture to view the join date displayed on their profile page.
Step 1: Open the Telegram App
Start by launching the Telegram app on your mobile device or computer. Ensure you are logged into your account to access all features seamlessly.
Step 2: Locate the Contact
Navigate to the Contacts section within the app. Look for the contact whose account creation date you want to know. Once found, tap on their name to enter their chat page for further details.
Step 3: Check Profile Information
On the chat page, tap on the contact’s profile picture at the top. This action will open their profile page, where you can find the date they joined Telegram. This date is indicative of when their account was created.