Someone who works for you made a decision without asking you, and he made a mistake. You are a little bit angry, and you want to make sure this doesn't happen again. You say:
From now on, check with me before you do that.
When you say to do something "from now on", it means to start doing it now and to always continue to do it that way.
When you use "from now on", it sounds like you are a little angry or not happy with how something was done. A more neutral (and formal) way to express this idea in a business situation is "going forward":
From now on, contact Jared if you have any legal questions.
Going forward, please contact Jared with any legal questions.
Some English learners use the expression "from now", but that's incorrect.
To "check with" someone means to ask them if something is OK:
You should check with the airline and see if they charge a fee for checked baggage.
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