The Save to Laserfiche task in Forms is asynchronous, so you would have to add a delay to your workflow to make sure it has all the documents. On the other hand, since this workflow would have to wait for the attachment documents too, you would need a delay anyway even if you start it from the entry creation event in LF.

If all the form data you need is in fields on the form document itself, then I would start the workflow from the document creation in LF, wait about 10 min and then read the fields and find the attachments. That way you would have the document already and you wouldn't incur the cost of connecting to Forms (it's not much, but if we're counting calls for efficiency, then it's worth considering).

I'd have Forms file the attachments into a subfolder of the folder where the form document is filed so I can use Find Entries by path to get them. OR ,if the form document and the attachment are saved in the same folder, then I'd have Forms give the form document a different template so the workflow only starts on that document. Then I'd use Find Entries by path on the %(Entry Path) token to get the attachments.