There is some good advice on life annuities in this Money Magazine Article.
How much should you convert? Enough to make you feel comfortable that you have a guaranteed income that no one or no government can take away.
Should you invest everything into a life annuity? No, you should keep enough for emergencies, perhaps in a 30 day certificate that rolls over automatically.
Should you wait till interest rates go up? Yes, if you are 40, no if you are 60 and beyond. Interest rates and your age are the 2 key elements in an annuity and you could wait and wait and not be able to make up lost payments. And with medical advancements life expectancy is increasing which is lowering payments for life annuities.