You can pay the first installment of estimated taxes by July 15. The amount that you should pay depend on your marginal tax rate. For example, if your marginal tax rate is 24%, you should pay 24% of the amount you treceived. If you do not expect any more exceptional income for 2020, you do not need to pay any more estimated taxes.
You do not need to file a quarterly tax return. You can pay estimated taxes at www.irs.gov/payments