If you will be out of US for more than 330 days, and it is spread across two years, then file extensions/don't file your taxes until the 330 day time frame is met. Use those dates as your 12 month period. Your foreign income in the first year 4 months of employment (last 4 months of the year) would be the 4 months of that year divided by the number of days in the year, or 122 / 365 = 33.42%. 33.42% of the maximum foreign earnings exclusion would be your maximum for that year. So for 2017 the maximum was 102,100. Your maximum amount that could be excluded would be 102,100 x 33.42% = 34,121. Your 12 month periods can overlap, so for the next year you could start at 1/1 or wherever to get you the most income excluded. You may want to Google Foreign Earned Income Exclusion-Physical Presence Test too.
