אין מוקדם ומאוחר
According to Rashi the last Kapital Tehillim Dovid wrote was Kapital 72 and ended it with the Pasuk כלו תפלות דוד בן ישי
There are different Mesoros to how many Kapitlach,
Tehillim consists of.
a) Our Mesora is 150.
b) The Yerushalmi (Shabbos #16 Hl.1) says there are 147 Parshiyos.
c) The Meieri on Tehillim has 151