Sorry, I should have included the dates for Ferdinandus(2)'s will and probate: dated 25 June 1737; proved 2 May 1744.
The indications are that Ferdinandus^2 married Gertruy in 1698 (on 10 September 1698, his father deeded him land in Kings County, Long Island, which probably establishes a date close to Ferd(2)'s marriage--before this he was living at home with his parents; see the 1698 census, Kings County [O'Callaghan:Lists]). In 1702, he purchased the Lady Moody House, so-called, in Gravesend, Kings County, Long Island from Nicholas Stillwell, Jr. [Rosalie Fellows Bailey, Pre-Revolutionary Dutch Houses and Families:59/60]. This is where he lived until his death.
So far as I know, the only bona fide dates we have to work with on the children are daughter Elizabeth(4) Van Sicklen (baptized 18 April 1704, Brooklyn RDC) and son Minne(3) Van Sicklen (baptized 23 March 1716, Gravesend RDC).If we follow the order of birth suggested by the Ferdinandus^2 will, Rensche^3 was born before Elizabeth^3. Which is to say, Rensche was born between 1698 and 1704.
I can't get closer than this from my sources, but perhaps someone here at the GenForum can hone it down finer.
PS--I am certain that the ancestry of Gertruy Minnes Johannes is documented, but I have not focused upon this.