I don’t know what the longest first line ever published is; but my 38 beats your Moll Flanders by many words and many more characters :-)
LETTER THE FIRSTMadam,
I sit down to give you an undeniable proof of my considering your desires as indispensable orders. Ungracious then as the task may be, I shall recall to view those scandalous stages of my life, out of which I emerged, at length, to the enjoyment of every blessing in the power of love, health and fortune to bestow; whilst yet in the flower of youth, and not too late to employ the leisure afforded me by great ease and affluence, to cultivate an understanding, naturally not a despicable one, and which had, even amidst the whirl of loose pleasures I had been tossed in, exerted more observation on the characters and manners of the world than what is common to those of my unhappy profession, who, looking on all though or reflection as their capital enemy, keep it at as great a distance as they can, or destroy it without mercy.