Level 1
A bit late, but just in case someones comes across this in the future.
You can use the methods provided by Cashier to get information about the billing cycle.
So you can get the current billing start date like this:
$subscription = $user->subscription('default');
$lastPaymentDate = $subscription->lastPayment()->date();
I can't post links so here are the relevant docs:
/docs/10.x/cashier-paddle#past-and-upcoming-payments