What's the date the 1870 census pinpointed his family in Saline County?

Date of enumeration is 3rd July 1870.

Alexander Brooks is listed as infant 4 months old which makes his birth in February 1870.

Name Infant Dickson
Age in 1870 4/12
Birth Date Feb
Birthplace Missouri
Dwelling Number 217
Home in 1870 Arrow Rock, Saline, Missouri
Race White
Gender Male
Post Office Arrow Rock
Household members
Name Age
Geo Dickson 71
Mary Percell 31
Catherine Dickson 24
Josiah Dickson 22
Nancy D Dickson 21
Sarah P Dickson 19
William Dickson 17
George Dickson 8
Netty Dickson 3
Infant Dickson 4/12