How often should one read?

Nityam bhagavata-sevaya [SB 1.2.18]. As a matter of principle, devotees should read, speak and hear Srimad-
Bhagavatam persistently, twenty-four hours daily if possible. That is the recommendation of Sri Caitanya
Mahaprabhu.

Kirtaniyah sada harih [Cc. Adi 17.31].

One should either chant the Hare Krishna maha-mantra or read Srimad-Bhagavatam and thereby try to understand the characteristics and instructions of the Supreme Lord
Srimad-Bhagavatam 5.6.16