Hi Neeraj,
Based on the current v0 pricing docs, credits work like a prepaid balance and each plan includes a monthly credit allowance. Premium includes $20 in monthly credits.
The docs also say unused monthly credits roll over to the next billing cycle and expire after 65 days. So if you upgrade now, I would not expect the Premium credits to last only until your current Free-plan reset date. They should follow the v0 monthly credit rollover/expiration rules instead.
That said, the exact billing-cycle start date after upgrading is something Vercel/v0 may need to confirm. The safest practical answer is:
If you need Premium now, upgrade now.
If you are trying to maximize included Free credits, wait until your Free credits reset.
Unused monthly v0 credits are documented as rolling over to the next cycle and expiring after 65 days.
If the timing matters financially, I would still ask Vercel Billing/Support to confirm the exact renewal date before upgrading.