I guess it is an "individual" thing. Like bill, I've seen very mixed results with new grads in the ED. The sink or swim thing is TRUE --- off orientation, you best be able to keep up, sure I always will answer questions/help - but, I will usually have my own nightmare assignment going on!
Not sure what your story is - some do make it though?
Do you have prior experience in healthcare?
As far as TNCC - I would do this in 6 months or a year, It is a 4 YEAR completion - so, I'm not too sure how much you would meaningfully retain unless you were able to incorporate the course into actual practice.
CEN - is Board Certification in Emergency Nursing. The BCEN reccs 2 years ED practice. Also, an individual thing here too. Did mine 5 months post NCLEX, passed easily - but I had been a medic for a long time.
Bottom line -
How well do you critically think?
What kind of prior experience do you have?
How prepared do you feel?
What kind of emotional maturity do you have?