I believe all the FEs that were scheduled to be built (there was a limited number), were built first before all other variants that were subsequently ordered. These were all delivered between March and July I believe.
However, the success of the FE model was not anticipated, it was so successful that all allocated stock had been sold within 24 hours of the launch night. In the meantime Dealers continued taking orders over the next few days. When they realised they had a problem the bigwigs at Volvo had a meeting during the week following the launch and decided they would fulfill all the orders already taken, and extend the order book for the FE by another 3 weeks (I think). Trouble was, slots had already been allocated for building other variants of the XC40, i.e. R-Design, Momentum, and Inscription. Therefore, slots had to be shuffled to insert additional runs of the FE later in the year. This was further complicated by the factory running out of certain items (e.g. headlight washers, certain wheel types/sizes, heated windscreens, etc.), all of which caused further delays.
I ordered my FE on the Saturday morning after the launch (which was on a Thursday in February), and took delivery of the car 3 months ago.