Since someone downvoted this, I feel I must explain what's going on here. Proto-Germanic did not have a future tense at all. All modern Germanic languages have developed (composite) future tenses, but English is the only one in which its use is obligatory. In the other Germanic languages, and in particular in Dutch, it is perfectly normal to use the present tense where future tense is required in English - so long as there is even the faintest hint of futurity in either the sentence or its context.
It's the same as for the Dutch progressive: Normally you only use it to stress progressive aspect or futurity or when it's not implied by the context.
Therefore, "He will start immediately" is actually a better translation because it's a more likely meaning of the Dutch sentence.