Cell Phone Towers

I live in MacDonald Ranch in Henderson, NV.  Within the last year a Cell Phone Tower was erected in the MacDonald Ranch HOA parking lot by Verizon.  I understand that T Mobil and ATT have signed on to use the tower for their service. To my knowledge Verizon is transmitting, however T Mobil and ATT are not.  When can I expect T Mobil to start using this tower.  Our service here is not very good.