General:
* Beginning: This is the most general option, and it's often used when talking about the start of something.
* Dawn: This refers to the early morning.
* Start: This implies a point in time that is before the usual or expected time.
* Premature: This refers to something that happens earlier than it should.
Specific:
* Morning: This refers to the early part of the day.
* First: This refers to the first of something in a series.
* Prior: This refers to something that happens before something else.
* Antecedent: This refers to something that comes before something else in time or order.
Informal:
* Early bird: This refers to someone who is up and active early in the morning.
You'll need to consider the specific context of your sentence to determine the best noun to use. For example:
* "She arrived at the beginning of the meeting."
* "The dawn was breaking as they set out on their journey."
* "They made a premature decision."
* "He was known as an early bird."
I hope this helps!