Early work is mostly the worker's own time reconstructing records, plus a scoped review by counsel. Late work adds urgency, duplicated effort and choices made under pressure. Any option identified may carry its own separate preparation cost, which is far easier to budget for with notice.
Buy the review, then decide
Ask counsel to price the chronology review and options assessment as a discrete piece of work. Its output should be a written reading of the record and a short list of approaches worth pursuing, with what each would require from the employer. Only then commit further spending.
Confirm any official charges at the time of the relevant step, and do not build a household budget around an assumed outcome. Add one further scoping question: what the review costs if the record cannot be completed. Some periods genuinely cannot be documented — an employer that no longer exists, a representative who has closed their practice, records destroyed under a retention policy — and a chronology with honest gaps is a different input from a complete one, producing a more qualified reading and possibly further work.
Establish in advance how gaps are handled and whether a second look is billed again once a missing item is later found. Hypothetical example: a worker's file is complete apart from an eight-month period held by a former representative who has retired, and agreeing in advance what happens to that gap prevents a dispute about scope at the point the reading is delivered.