Can we validate date in Amazon Lex?

Question

I have created a Hotel Management lex bot that makes a reservation for hotel rooms. I am using slots (Check-in Date and Check-out Date). I am using built-in slot that is Amazon.Date.

Problem

I want to restrict customers at this stage so that customers can only enter date that matches with the current date or after the current date. Currently, these slots are accepting all dates including previous dates.

How I can validate these slots? (Can we solve our problem with RegEx while using Amazon.Alphanumeric type)

What are the possible solutions?

Should we handle this in Lambda? (If yes, kindly describe how I can get the Elicitation value of a slot in Lambda (Python)).

What would you prefer me to resolve or achieve this?

Any help would be greatly appreciated and thanks in advance.