In the beginning...
What type of beginning? A beginning of our universe? A beginning related to life and its existence (thus in the context of the purpose of Genesis)? A beginning that includes everything God created (angels and spiritual realm also)?

the heavens and the earth...
Most translations agree on these specific words. Not "Heaven". Notion of above and below and everything in between. (particularly in the word meaning of ancient cultures such as Chinese and Hebrew.) The intent here is that God created everything in existence.

So this first verse address all of time and space as we know and comprehend our existence, in the physical realm.

However, given that the writer (Moses) has a cosmic world view that integrates spiritual and physical realities, we should not constraint "existence" only to our current cultural view of "physical" realm. Allowing for this possibility, we see the Bible focus on our daily physical dimension, but slowly draws us toward the spiritual realities, without burdening us by all the details of the spiritual realm, how it was created, how the angels were created, ... He focus on how we are created, how our everyday life and world works and revolve around Him. Basically, focus on the main thing. Don't be distracted by secondary issues.

Stretching out on a limb, we can always have the interesting exercise of discovering the spiritual counterpart of every lesson in the physical realm. But staying with the proper reading of the Bible text, we should just read the text for what it says. (of course, always allowing God's inspiration to come through any text at the appropriate time of our lives, when we prepare our attitude and expectancy before coming to His Word.)

Genesis 1:1