I have the 1969 published "The Escoffier Cookbook and guide to the fine art of cookery" which is a translation of the book Guide Culinaire published in France. On page 180 under "459-Scrambled Eggs" he says this, if it is of any assistance...no time mentioned:
"In old cookery, scrambled eggs were sanctioned only when cooked in a bain-marie. This measure certainly ensured their being properly cooked, but it lengthened the procedure. The latter may therefore be shortened by cooking the eggs the usual way, in a pan in direct contact with the fire; but in this case the heat must be moderate, in order that, the process of cooking being progressive and gradual, perfect incorporation of the eggs (effecting the smoothness of the preparation) may result."
Sorry that's all I've got. Except the number 157 might be the number of the entry, like the 459 above.
