Timing of marriage

hello ,this is akash, I have a basic dout on marriage gift,
my brother's marriage is on November,but his fiancee's Father wanted to gift a cash and deposited in his bank account September,


my question is whether marriage gifts AT THE TIME MARRIAGE CONSIDERED or ON OCCASION OF MARRIAGE CONSIDERED (regardless or near by time frame)

should I need to tax the above or no need to tax the above ...?