Weather, to answer your question about measuring time before there existed an Earth or a solar system: the second is currently the fundamental unit of time. That is, all other measures of time are defined in terms of seconds.
The second is defined in terms of a measurable physical phenomenon, in particular, it’s the amount of time that it takes for a certain type of radioactive cesium atom to decay a certain amount (or some such).
So it’s certainly possible to consider time before the Earth existed.
More fully on-topic, there’s a fascinating article I read recently which says that science and Genesis may be much more in agreement than is generally thought. As Einstein said, time depends on one’s perspective.
Basically the thesis is that from our perspective looking back, we see 14 billion years or so. But starting from the point where energy first condensed into matter and looking forward, it works out to about six days.