Biogrow and biobloom

My plant is in week 4 and about to give it its first nutrients.

How much biogrow should I give my autoflower and how often?
And when should I switch the biobloom?
When I switch do I give both nutrients or just stick with biobloom?

First feed give it half the maximum ml at least. Better to safe than sorry, even a quarter of the recommended dosage.
That's just general rule.
If your leaves are nice and green then no problems so far. Pics would help. Advice is only generally. Each strain and plants differ.

Using biobizz I would recommend the acti vera first, bio grow. Save bloom for later in calendar. Follow the guide so to say.
Better to under feed them than over feeding.

in flowering use both grow and bloom

Half the maximum at most# not least as I typed.