Crosslinking of a crosslinkable viscosifying agent and a crosslinking agent may be delayed in a well treatment fluid by incorporated within the fluid a glutamic-N,N-diacetic acid salt, such as a glutamic-N,N-diacetic acid sodium salt like tetrasodium glutamate diacetate. The crosslinking agent may be a zirconium containing crosslinking agent like zirconium (IV) acetyl acetonate. The viscosifying agent may be guar or a guar derivative such as carboxyalkyl guars and hydroxyalkylated guars like carboxymethyl guar, hydroxypropyl guar, hydroxyethyl guar, hydroxybutyl guar and carboxymethylhydroxypropyl guar.