[Babul]

usually the SendClientMessageToAll() gets used for sending a chat to all players. what you need, is an array holding all players, with a value to allow the chat output:

Code:

new AllowChat[MAX_PLAYERS];

then, instead of SendClientMessageToAll(), make a loop, checking if the AllowChat[playerid]==1 - if set to 0 (when logging in, ergo not set to 1 before spawning), then dont send the chat line. this will require a bit processing time due to the loop:

Code:

public OnPlayerText(playerid, text[]){
//SendClientMessageToAll(0xffffffff,text); //disabled this, and replaced by the following loop:
new MaxPlayers=GetMaxPlayers();
for(new id=0;id<MaxPlayers;id++)
{
	if(AllowChat[id]==1)// dont forget to set this to 1 when spawning!
	{
		SendClientMessage(id,0xffffffff,text);
	}
	return 1;
}

suppress chat on skin selection (i would use the OnPlayerConnect here aswell)

Code:

OnPlayerRequestClass(playerid, classid){
	//...
	AllowChat[playerid]=0;
	//...
}

to allow the chat after spawn:

Code:

OnPlayerSpawn(playerid, classid){
	//...
	AllowChat[playerid]=1;
	//...
}

not tested, its the concept idea only, but i hope you get how simple it works ^^