Sorry, I assumed that had already been done.
In order for your pets to travel, you'll need to take your documentation (EC 998, microchip proof, rabies certificate, FAVN form) to your state's USDA office to get them to sign off on the EC 998 (section V, if I remember correctly - my form is in the US with my pets).
In NC, it cost about $120 to do 2 pets..I think it was $110 for one and $8 for the second pet. Also took about 1 1/2 hours because they weren't so observant of the fact that I had made an appointment to come in.

You can do that at any time, really, but once the USDA stamps their date on it, it's only valid for 4 months after that date.
I would recommend getting the USDA signoff asap (unless you don't plan to fly your pets before July), and then you're free to book their flight and do the tick/tapeworm visit.
And yes, you'll need to send your forms to the US to be with your pets - they definitely won't accept photocopies or anything. (And they won't accept your word that you have the paperwork here waiting for them

).