I assume the both Kodak and Ilford have a good reason for not recomending pre-soaking.
Both companies recommend you use of a rapid fixer with T-grain films because silver iodide is slower to remove than either the chloride or bromide salts. A dark stain may indicate insufficient fixing and/or washing. Use of aa alkaline HCA will also reduce the amount of dye. Dye retention is more probable with low pH developers.