ever seen a 5 man rush from min 0:00?

Early game pushing is hard, and it does depend to a point on how your team plays it and what heroes you have available. Good AOE nukes are at a real premium. Ideally I'd say call in your supports from the other lanes and try to hold the tower for as long as possible, every minute extra it takes them costs dearly - that way you've got 2 players getting free farm/max levelling who can come in and turn the tide a little later.

A big one for the long laners is to pressure their safe lane tower by pulling their lanes using neutrals, and obviously good anti-push heroes will really help too.

Biggest problem in pubs is that you have to co-ordinate and change your builds - which a lot of people are relucant to do. Maybe you need to spend all your cash on Clarity Potions and feed them to your support with an AOE spell. Anyone even looking at a Battlefury or Hand of Midas should be shot :)

while i have no personal experience with big pushes early game, i have seen i pro games when they use such strategies (lets say 4man mid with a carry farming he easy lane) the opposing team goes 4 man in the hard lane to pressure the carry and hopefully(probably) psuh a tower, all while the carry freefarms the easy lane.