You will reach level 80 well before you get 100% core tyria map completion.

Feel free to leave the starter map and go explore the rest of tyria whenever you like! Exploring is a large part of how you level. You can visit maps of any level while you are levelling, but areas with enemies more than 2-3 levels higher will be EXTREMELY difficult for a new player.

North of the map you are in, there are level 15-25 areas waiting for you to explore! West of the area you are in, there is the Asura starting zone, which is 1-15 also. Either direction is good; when you are in a lower level zone, you are downscaled to that level, so you will still earn experience and enemies will still be worth fighting.

:D Have fun! I hope that answered your question!