query string or url hook Varnish caching

I want to ensure that our WooCommerce variable products display prices to customers based on exchange rates updated in prior 24 hours. Our site uses Varnish, so pages are cached. I’m considering 2 approaches:

1. set the Varnish TTL to 24hrs, or
2. exclude identified query strings or url hooks, for example fmelearnonline.com/?woocurrency from Varnish.

Which, if either, is the best way forward.

Thanks for your help,

Best,

Mark