There is no short-circuit evaluation of boolean expressions in BASIC so it often pays to cascade IFs and put the expression most likely to be false first.
In BASIC, AND always evaluates both operands even if the first is false.
An oddity of the BASIC language, but useful to know since it goes against "modern" languages.
This might read as optimised (as the first clause is least likely):
IF %g=208 AND (j=0) THEN %j=1
But it's better/faster written like this:
IF %g=208 THEN IF %j=0 THEN %j=1