Renting an SEP once a month is not going to help you at all. The difference between 250 hrs and 300 hrs means diddly squat.
Assuming you hold CPL/IR, an instructor rating is available to you right now. If you have parachute or gliding experience, that avenue may also be open.
If Air taxi is available in your part of the world, think 700-1000hrs might do it.
If you weren't on a tagged airline scheme, or willing to join a pay for type cadetship, you can forget the airlines.