The same thing happened to me around 10 AM on a mid-September day in 2022 (yes, quite possibly more people will be in Venice in April of Holy Year 2025). I arrived to find quite a long line. The folks right behind me in line assured me the line would move fast, and it did. I think I reached the door in about 30 minutes. While your wait this year might be longer, I don't think this is going to destroy your day.
Arriving earlier would likely mean a shorter wait, because a lot of the tourists you see in Venice are not staying in the city, so they may not get to San Marco particularly early. However, you might want to know that they illuminate the interior of the church late in the morning--sometime between 11:30 AM and noon, I believe. I really liked the better view of the mosaics afforded by the illumination, but I can't say I was bothered by low visibility before they turned on the lights--and I'm old enough that seeing things under low light conditions can be a challenge.