Если бы они начали эту работу сразу

Если бы они начали эту работу сразу, они смогли бы закончить ее вовремя.

Результаты (английский) 1:

If they'd started this work immediately, they would be able to finish it in time.

Результаты (английский) 2:

If they had started the job immediately, they would be able to finish it in time.

Результаты (английский) 3:

if they started the job soon, they would be able to finish it on time.