TI well anytime you see people. I recomend you join an active group, its usually easier to do TI with group members or/and friends.

As far as Arena, if you are not cross server yet it will be very hard for you to find matches in your server unless you do it deliberately with other players. Even then the mathing algorithm is weird and its criteria is unknown. Once you get cross server, if you do not have over 12k total initiative, wait till the end of the month. By then most stron players have already reached sage of the 6 paths rank and you can get some wins even at kage level.