Quoting from chan:
"About the release date, Animo said that he "hope to finish the "animation" in 1,5 months. Then i will start rendering", so for good measure, let's say that Animo begins rendering at the end of February.
Animo also said that part 5 is "probably going to be the longest episode so far... I was trying to make it shorter, but as usual - added couple of things here and there."
The longest part so far is part 4, with 35 minutes. The first rendered preview was posted the 3rd of April, and the no sound version the 1st of June. (2 months)
So the (no sound) release date of Breaking The Quiet Part 5, is probably going to be in May, so 4 months to go.
Animo confirmed, regarding Quiet, that "Yes, there's gonna be couple more scene with her of course."
also, take this as the best case scenario. I woudn't expect anything before June.
TL/DR: It's not going to be released in March or April