We had a job start 9/1 and a subcontractor filed a Notice to Owner dated 11/4 in the state of Florida, with that document needing to be within 45 days of first providing labor and or material to the jobsite does that mean the Notice to Owner is invalid?
The deadline to send a Florida Notice to Owner is 45 days and, as you noted, this 45 days is measured from the date the claimant first provided labor and/or materials to the project. The start date of the project isn't factored into the preliminary notice requirements. That being said, if the notice was sent past 45 days after the date the subcontractor first furnished labor and/or materials, then that notice will likely be deemed invalid for the purposes of securing lien rights in Florida.
One last thing to note is when the notice is considered served under Florida's lien laws. If the notice was mailed by the required method to the appropriate address within the first 40 days of furnishing, the notice is considered served on the date the notice was deposited in the mail. If sent after, it only becomes effective upon actual receipt of the notice.
For more on Florida preliminary notices, see: