Another "yes", unless a mechanism is created to make sure votes are not duplicated, amd not opened or counted until the prescribed "official" day.
Additionally, the reason for absentee voting should be narrowly defined, and not trivial, as simply for "convenience."
Civic duty doesn't tolerate "convenience."
The OPERATIVE clause is:
The Congress may determine the Time of choosing the Electors ...
Since Congress has determined that 11/4 (this year) is Election Day (the Time of choosing electors), it seems to me that any early voting law enacted by any State is unconstitutional.
I refer to:
Article VI (2):
“This Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every State shall be bound thereby, anything in the constitution or laws of any State to the contrary notwithstanding.”
This supremacy clause has been called the “linchpin of the Constitution”, since when state laws conflict with national laws enacted within the powers granted to Congress, the national laws prevail.
Since Congress has determined what day is Election Day, and has made NO allowance for States to enact their own early voting laws ... early voting should be unconstitutional Q.E.D.
Anyway - thats my 2 cents ...