Turn Based game not in Sync

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I am making a turnbased game using Photon classic. Everything is working fine, player creates a room, other player joins and both players can play from start to end. The problem is with synchronization of turns. I am using this code to start new turn when player joins the game:

if (PhotonNetwork.isMasterClient)
{
turnManager.BeginTurn(); // calls OnTurnBegins function
}

I have set 5 seconds time for each turn but the turn for players doesn't start at same time. The masterclient has a headstart of 1 or 2 seconds at the start of 1st turn as a result of which the other player doesn't get all 5 seconds for the turn. Any help here?