Same match different odds is this normal or am I missing something?

I'm using site for about three weeks and I'm still figuring a lot out, so I decided to ask more experienced people. This morning I placed a bet on a match - the odds were at a certain level. Then I went to the office and talked with my colleague, who tried to place a bet on the same match a little later than me. He had noticeably different odds for the same outcome. So I'm wondering how common it is for odds to change. In other words, is it better to place a bet later or closer to the start of the match, or does it depend on something completely different? I need to decide on a strategy before the upcoming tournament in India. I've had some success, but I don't want to rely on luck or guesswork. I still don't fully understand how it all works and I'm trying to learn the logic so I can plan better next time. Are there experienced users here who could explain how this works?