Beginning and ending are time ordinals which only have meaning within the stream of elapsing time. The words have no meaning apart from the reality of time. Therefore, time is not only a dimensional aspect of the created order because Einstein theorized it so and findings afterward verified that; but also because, philosophically, time ultimately is entailed within creation. Time is nothing more than something that passes sequentially between ultimate beginning and (potentially) ultimate ending.
Time is wed to created things: it's locked into initiations and progressions. Time cannot exist substantially where there is no beginning, what would it be? It cannot exist in the realm of the ultimate creator, in the place that is other than creation, or that place, that person, wouldn't be without a beginning. Some theologians have been saying for centuries that God is outside of time--they spoke well; for if time is an attribute or aspect of God, then God is subject to time as is any created thing, and his self-contained existence is undermined.
Logicians can have difficulty with such a concept because of the necessities of order in logic. Some thoughts have to occur before others in sequence. I think that situation is more a consequence of our thoughts and experiences being locked within the created order than it is of any ultimate truth in the realm of the ultimate creator. All that can be truly said, I think, is that logic works that way in our realm of elapsing time. Who among us can know the mind of God?