How long should you wait to txt someone after a first date?

The Breakfast Club 19/09/2018

One of Sam's friends went on a first date recently. The date went well and Sam's friend got the guys number.

When Sam asked her if she had txt him yet, she replied that she wasn't going to txt him for 3 days, so she didn't come across as 'too keen'.

Sam asked the rest of The Breakfast Club if this '3 second rule' should be followed.