Yes. You can tone before, after and while fixing. But in the normal case:
before.
-After: is usually a conservation process of an existing picture.
-While: a poor quality process which was used to make a large amount of
copies when the POP was the basic material of professional photographers,
or as a simple method for amateurs.
-Before: the best way to control the color, contrast and durability of
the picture by several receipts and versions of toning.
Briefly: an alkalic toner is the faster, the best for conservation and
to increase the maximal density of print but expensive, the acidic is the
opposite of this one, slow and weak by result but cheap. The good compromise
is the neutral, which is widely used in the modern practice it is usually
working with several thiocyanides so it's a dangerous poison.
A "modern" neutral example (Source and more details: Fundamentals of
Photograph Conservation Toronto 1991. 185 p.
- in memoriam Klaus B. Hendriks.):
Kodak Gold Toning Formula T-53
Stock Solution A
Ammonium thiocyanate 10 grams
Distilled water to make 500 mL
Stock Solution B
Gold chloride 1 gram
Distilled water to make 500 mL
Working Solution
Solution A 15 mL
Solution B 15 mL
Distilled water to make 500 mL
By color of density all version of receipts, processes and photographic
materials are different.
Balint Flesch