Group education on  infant formula is not allowed under BFHI
criteria, Step 3.  The assessment specifically investigates this.

Also, the WHO Code, Article 6.5
"Feeding with infant formula, whether manufactured or home-prepared,
should be demonstrated only by health workers, or other community workers
if necessary; and only to the mothers or family members who need to use
it; and the information given should include a clear explanation of the
hazards of improper use."

This means no pre-natal instruction, unless you can somehow identify and
single out during pregnancy those mothers "who need to use" infant
formula (eg HIV+ mothers in some settings).

Hospitals in Australia have found that one-to-one postnatal instruction,
actually supervising the mother mixing up feeds, is much more supportive
and educational. Who says mothers learn better in classes? By all means
pick out the mothers who are bottlefeeding and give them responsible
one-to-one assistance, just as you would help a breastfeeding mother have
difficulty latching on. Bottlefed babies need all the help they can get to
ensure they are fed correctly.