When the center is blocked. That is the best time to start a flank attack, because your opponent cannot couunterattack in the center when the center is blockedd. It gives your flamk attack its best chance of succeeding.
When and how to do a minority attack on castled side

As an example, when your opponent--let's say Black, kingside castles into a fianchetto structure, and you queenside castle... the h pawn becomes dangerous as the g6 pawn gives it a 'lever' to pry open with. So stopping that plan will become a major idea for Black and facilitating it will be something you should consider.
The Yugoslav Attack in the Dragon is a quintessential example. The Albin Counter Gambit is a good example with colors reversed.
The situations where you pawnstorm with the pawns in front of your king are different. If you have good center control, or the center is locked down perhaps it becomes a plan. Otherwise this becomes very risky. But it can pay off. Check out some games with the Pirc Austrian Attack, where that can happen.
Well this is actually a mid ga,e question but there's no mod game section sooooo..... What tactics and situations are good for pushing your pawns forward when both sides are castled on the sale side? I know that moving pawns from the castle weakens it which is why I try to avoid it completely , however I see the possibilities it has for attack and pressuring the opponent especially when you have a bishop pair and maybe a knight with your queen