What’s the best time of day for Yahoo answers?

Best time of day for what? Your post is vague. Assuming you mean the most activity, it tends to be fairly busy here during the day (US Time) and in the evening (US Time) when people get home from work and piddle online for a while.

Whenever the USA (and most trolls) are asleep

"Best" is hard to define. The most users are on YA during these times.

 Teens 4-8pm New York time Monday-Thursday

 Adults 6-10pm New York time Monday-Thursday

 For computers, ask early in those times. If you are asking a local question for say London, adjust those times for the city involved. Holidays and weekends are bad. Forget Super Bowl Sunday.

This site is Global so there is always someone on this site who will answers questions, of course it does also depend on which category that your questions have been submitted and whether or not the users are visiting that category.  So submitting questions and answering is entirely up to you.

Anytime but be sure it's not in the late evening

In my Opinion Early Evening so like after 7 pm thats when a lot of people get Home from Work and or School and get Settled in for the Evening and have Free Time so they hop onto there Phone Tablet or Computer and Sign on

all depends  who your peeps are, and what time of day they are on. 

My own personal observations, is that early morning , for me  in Italy time....GMT+1 

is the best time......because a lot of fun people are on at that time.....or have just recently posted their strings of questions, and there's lots to answer. 

That's  either a lot of night owls in other time zones or early birds here in Europe. 

I find the worst time to be on----is clearly 3 pm to 6 PM  my time. 

That coincides with 9 am to 12 pm  east coast time..(USA) ....and that appears to be when most political trolls are on. ...spewing all their hate and garbage. 

seems to coincide with people who have dead end jobs, and play on their computers from 9 am, to  lunchtime. ...or worse...........play all morning, while someone else goes to work pay their bills. ---so they have all morning free to stalk and harrass people here. 

The time they have the most users online is in the USA east coast time from 3 pm to around 10 pm weekdays.  Holidays and Weekends will be less on line.

wrong. night time is better for Y!A. NO DAY.

None. Y!A is 24 hours. Send away. Questions can wait for weeks getting answered if no one rogers up, or a Best Answer is not chosen.