From when the Duration of stay starts?

Hello Guys

I have a confusion about duration of stay, I will be arriving on 11.00 a.m. at TPE. I applied for 60 days for what i bought a confirmed round trip ticket. But, they only gave me 14 days tourist visa. So, I need to modify my round trip ticket. According to NIA, the duration of stay starts from the day next of your arrival, is it true? as there is confusion if it is only applicable for Visa-exempt passport holders. Please help!

Thank you