Here is a version from February 2014:
skyscrapercity.com/showthread.php?p=111294331&highlight=harmonogram#post111294331 - I have no idea if it has changed or not.
Seems that the official deadline is (or was) June 2016. As you can see in the posts below, even in that time people didn't believe that they will do it until 2016.
Here: skyscrapercity.com/showpost.php?p=125719114&postcount=2836
someone says that theoretically the end of the Tłuszcz-Zielonka section upgrade is with the end of 2016, so probably they extended the deadline. Others say that they will probably end the four-track section (Wołomin-Zielonka) in 2017.
I have asked the people there and that's what they answered:
Termin oddania odcinka Wołomin Słoneczna - Zielonka (LK21) to 1 lipca. Moim zdaniem powinni zdążyć.
The deadline for the section Wołomin Słoneczna - Zielonka (railway line No. 21) is July, 1st. In my opinion they should manage to do it on time.
Jeden tor może zdążą oddać, ale nie cały odcinek z pełną infrastrukturą. Dopiero jak przełożą ruch na tor lokalny (jeden tor, a nie oba) za kilka tygodni (a raczej już miesięcy), to zaczną rozbierać ostatni stary tor i budować tunele pod tą częścią torowiska.
Maybe they will manage to finish one track on time, but not the full section with full infrastructure. Only when they switch the traffic to the track for local trains (one track, not both), they will start to disassemble the old track and to build tunnels under this part.
Więc nie wiem, co miało być zakończone za trzy miesiące, ale na pewno nie będzie to odcinek Słoneczna - Zielonka.
So, I don't know, what is going to be finished in three months, but definitely not the Słoneczna - Zielonka section.