I would totally book my FP for Test Track and then switch when the one you want becomes active. You will definitely be able to change your FP selection at a later date.
The fly in the ointment is that you will have to monitor the Dis Boards and know
as soon as day one of when the booking window finally opens for Frozen/Soarin.
The possibility also exists that when Frozen/Soarin opens you may only be able to choose 1 from Soaring OR Frozen OR Frozen meet and greet OR Test Track. The "only one FP choice" from the above mentioned categories is
SPECULATION on my part. The reason for this may be to have guests return to Epcot more frequently to boost sagging attendance. When Food and Whine starts up this (potential) throttling will most likely end.
That's just my opinion. For those of you in need of more humorous content, please enjoy this gratuitous picture of an owl having her parade rained on.
Hoping not to disappoint,
~NM