I'm a subcontractor working on a large commercial job. I field a mechanic's lien last Friday, now I'm finding some articles about sending an intent first before the mechanics. I spoke with the owner over the phone and he said go ahead and file the lien.
A Notice of Intent to Lien (NOI) is only a required document in a few states such as Colorado and Illinois. It is not a required step under Florida's mechanics lien laws. However, even when not required, many contractors use this document as a final warning letter to try and induce payment before having to file a lien on the property. So in short, there is no problem filing a mechanics lien in Florida before sending an NOI.
Here are some additional resources you may find helpful: