New Testament

In the old testament the Jews had their own calendars and festivals, etc....when Jesus came he says " Do not think I came to abolish the Laws or the Prophets; I have not come to abolish them but to fulfill them." Matthew 5:17 So does that mean some of the festivals like the feast of unleavened bread except the sacrificial ones, are we still suppose to keep these? What about their calendar because it goes off of the verse "And there was evening and there was morning the first day" Genesis 1:5