It is your decision as to whether or not you want to make an estimated tax payment or payments. You are not required to do so and you can avoid any penalty for underpayment of estimated tax if you owe less than $1,000 in tax for 2019, or if you pay at least 90% of the tax owed for 2019 or 100% of the tax shown on your return for 2018, whichever is smaller.
With respect to your inheritance, the basis for inherited property is the fair market value on the date of death of the decedent. In this instance, your basis would likely be the fair market value on the date of death of your grandfather and, assuming you are only a beneficiary, you should check with the executor (personal representative) of the estate and inquire as to whether you will be receiving a Schedule K-1 (1041) and the period the K-1 will cover (i.e., whether it will be the 2019 calendar year or a fiscal year beginning in 2019 and ending in 2020).
Note that if your grandfather passed away in the recent past, there will most likely be little, if any, gain as a result of the stepped up in basis. Again, the executor would have the relevant details of the transaction.
