The basic rotation without Leylines is 3x F4, F1, 3x F4, Despair, B3, T3, B4 and back to AF with F3.
Since you use F3 to switch it's impossible to keep a Firestarter proc for Enochion refresh instead of a F1 during AF; it's something that can proc during your AF phase and can be used for movement/ weaving/ additional refresh, but it's never just there for the first mandatory refresh.
Xeno is used as a filler in UI if T3 doesn't need to be reapplied, not as a standard filler to get full ticks. Skipping on B4 without Leylines doesn't make sense as you don't have enough mana for 2x 3F4 rotation nor enough speed for the 5x F4 rotation.