New York's "convenience of the employer" rule basically states that if during the tax year you as a non-resident of NY work both within New York and remotely from outside New York, then your remote work income is taxable by NY if you are working remotely for your own convenience, as opposed to having been assigned or required to work remotely by your employer. Think of a CT resident who works in NY and decides on his own that he'd prefer to work remotely from home every Friday. NY would still tax all his income, even though his Friday income was earned outside NY.
Time zones, check-in times, etc., are irrelevant.
On the other hand, California does not tax non-resident W-2 employees who work entirely remotely from a location outside California. CA has no "convenience of the employer rule." A Texas resident who works for a CA employer, but who never physically works within CA, would not be subject to CA income tax on his W-2 salary or wages. (I'm assuming that your "LA" abbreviation stands for Los Angeles, not Louisiana.)
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
