How to get x,y coordinates of turtlebot

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Hello, I'm trying to get the x and y coordinates of a turtlebot in the simulated world. Currently I have subscribed to the odom topic and have been able to get pose.pose.position.x and pose.pose.position.y. However when I get these values they are not x=0 and y=0 as I expect as the turtlebot has not yet moved. Is there something wrong with my assumption and/or am I not using the right rostopic to get desired x and y values?

Thanks.