Leviticus 23 contains "the appointed festivals of the LORD". We can see these observed by Jesus and his disciples in the New Testament. Scarlett discusses a special day observed only by the priests in Having Believed.

Jesus gave the following instructions to His followers after he had risen:

On one occasion, while he was eating with them, he gave them this command: "Do not leave Jerusalem, but wait for the gift my Father promised, which you have heard me speak about. For John baptized with water, but in a few days you will be baptized with the Holy Spirit."
Acts 1:4-5

They obeyed. And when a festival of the LORD, "the day of Pentecost came, they were all together in one place" (Acts 2:1). As followers of Jesus, they still observed the appointed festivals of the LORD. On that day of Pentecost they received the gift promised, the baptism of the Holy Spirit.

The gift was not for them alone, but for those who would "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit" (Acts 2:38).

Paul tells us to:

Be very careful, then, how you live—not as unwise but as wise, making the most of every opportunity, because the days are evil. Therefore do not be foolish, but understand what the Lord's will is. Do not get drunk on wine, which leads to debauchery.
Ephesians 5:15-18a

We ask you to join us and

…… Be Filled with the Spirit, speaking to one another with psalms, hymns, and songs from the Spirit. Sing and make music from your heart to the Lord, always giving thanks to God the Father for everything, in the name of our Lord Jesus Christ.
Ephesians 5:18-20