How long will it take for my SSL certificate to be ready for my Shopify store?

I believe that it can take up to 24 hours for your SSL certificate to be ready, but usually, it takes less than 4 hours.

When your website is unsecured, your website address will be "HTTP://storename", so when your website address changes to be "HTTPS://storename", then you will know that your security certificate is active and working. 

If it takes longer than 24 hours to work, then you should contact Shopify support and ensure that everything is alright.