what are considered the "matinee times" ?

Before 4pm most days. they also have $5 Ticket Tuedays all day every Tuesday

I couldn't find anything on AMC's website but movietheaterprices.com says it is 12:00 pm-3:55 pm

Here is an answer from Quora "Yes. AMC Theatres breaks their pricing scheme into (3) different sets respectively. They are as follows: AM Cinema, Matinee, and Prime. I will list some details below, based off of actual information within the LA market. Please keep in mind that pricing varies greatly depending on a) what AMC location you go to, and (b) what market that theatre is in. (i.e. AMC Century City in the LA market). Now to answer your question and elaborate some... -AM Cinema (Open - 11:55am) is your cheapest bet, offering the best bang for your buck. Prices average between $6 - $7.50 per ticket, regardless of age. -Matinee (12pm-3:55pm) is next in line. Prices average between $9 - $11 per ticket, regardless of age. -Prime (4pm - Close) is the most expensive, as it is usually the time when most guests come to see a film, hence the term prime. Prices average between $12 - $13 per ticket."

What do you mean matinee time?