Adding a lock on a button until an item has been added to cart

Site URL: https://www.giftboxbysimona.co.uk/

Hello,

We have a customise your own box section on our website and I want to try and find a way to lock the 'Start Customising' button, and the only way to unlock the button is by adding one of our boxes to the cart.

The only reason for this is before you start customising you add a box to your order so you can customise the card and then press the 'start customising' button to start adding items.

Thank you!