You might not want to start testosterone without a level, just because the side effects of excess are both distressing (male hair growth patterns) and potentially harmful (worsening blood lipid profile). On the other hand, if you start with a very low dose of bioidentical testosterone and listen to your body very closely, you can follow how you feel (libido is good, rip-your-head-off aggression is excessive) and how you look (zits are an early warning signal, followed by moustache and balding) and decide if the stuff is for you. If you do not experience bad side effects, then it can take up to three months to feel the full good effects. So it may not be an immediate decision.
BTW--the normal ovarian output of testosterone is only about 0.25-0.3 mg a day, so we don't need much. Best luck seems to come with starting with no more of a dose than that (which requires a MUCH weaker preparation than the 2% ointment--a nasty stuff made with vaseline--that is all many docs know to write for. You may need a compounder to get a low strength cream.), and working up from there if needed. And testosterone needn't be taken every day. One way to control your dose is to take it intermittantly. I currently use it 2-3 times a week--and I know when I'm approaching the line, thanks to my "signal zit"--a particular place on my face where I break out at the first sign of excess.