FEIE & Stateside Move

I’m returning to live and work back in the U.S. this June. From an FEIE perspective, can I file a 2555 next year for 2017 and receive the prorated 180/365 for example of the $100k exclusion limit. Or must I file a 1116 and just take the credit for tax paid in the U.K. I would have worked in the U.K for several months up to my U.S. bound departure.
As I’m moving halfway through the year, I’m not sure if I’m a bona Fide resident of a foreign country, (U.K.) or if I’d meet the physical presence test for 2555 purposes.
Any comments would be welcomed
Thanks

Might you have any non-US workdays at any point in the next 10 years? If this is a possibility you'd want to optimise your "bank" of excess foreign tax credits carrying forward by not electing to claim the foreign earned income exclusion.