Obtaining the TTL for a domain is quite simple.
Open up a terminal and meet your new friend 'dig'.
Type the follow, replacing my website url with your own.
dig +nocmd davidheward.com +noall +answer
The response you will get is:-
davidheward.com. 3496 IN A 184.108.40.206
Your friend is 3496 this is your domains TTL.
Which is 3,496 seconds, or almost 1 hour.