Who are they waiting on?
The people waiting on the presence that Jesus promised that would make a difference in their lives. This difference would be that a person dwells within their lives. This understanding of The Holy Spirit a a persons is an important distinction to make about The Holy Spirit.
Very often you hear people refer to The Holy Spirit as a feeling. You will hear them say something along lines of, 'you could really feel the Spirit in that service.' I am not saying that one would not feel or sense something when The Holy Spirit is obviously present with His people. However, to associate the presence of The Holy Spirit with feelings is to limit one's understanding of The Holy Spirit.
The Biblical position about The Holy Spirt is that The Holy Spirit is a person. This is clear in the grammar of The New Testament. The terms used by Jesus when referring to the Holy Spirit are personal . Jesus makes this clear in John 14:16, 26 as uses the term "he." Jesus never refers to the Holy Spirit as "it" or in some impersonal form in grammar.
This means that those waiting in the room in Jerusalem are waiting on a person....not just an influence or impression. This is a radical thought if you give some time to think of it. We often speak of Jesus as residing in our heart but do we give much attention to the notion of the person of The Holy? What difference does this make as we proceed to Pentecost that The Holy Spirit is more than a feeling or an influence but a person to whom we respond?
REFLECT: Give some time to consider the person of The Holy Spirit and how that might affect view and experience with The Holy Spirit.