(

a) Except as provided in subdivision (b), regardless of their age, a child shall be deemed to have entered foster care on the earlier of the date of the jurisdictional hearing held pursuant to

Section or the date that is days after the date on which the child was initially removed from the physical custody of their parent or guardian. (b)

(1) When the court orders the custody of a child to be retained by the parent or guardian at disposition, even if the child was initially detained, and then subsequently removes the child at disposition on a petition brought under

Section or 387, the child is deemed to have entered foster care on the earlier of the date of the jurisdictional hearing held pursuant to

Section or or the date that is days after the date the child was initially removed from the physical custody of their parent or guardian on a petition brought under

Section or 387.

(2) The disposition on a petition brought under

Section or shall be considered the initial disposition for purposes of paragraph (1) of subdivision (

e) of

Section 366.21. (

c) For the purpose of calculating the date of a continued permanency review hearing pursuant to paragraph (1) or (2) of subdivision (

g) of

Section 366.21 or a subsequent permanency review hearing pursuant to paragraph (1) of subdivision (

b) of

Section 366.22, the child shall be deemed to have been originally removed from the physical custody of their parent or guardian on the date they were taken into custody by the social worker based on a petition brought under

Section or 387.