Litigation can be very time-consuming, and complex cases can involve a lot of preparatory work. You will need to check what documents you have that could relate to the issues in the case, which will probably involve going through a lot of correspondence and e-mails, as well as identifying the contractual documents. You will also need to meet your solicitor to provide him (or her) with full details of the background to the dispute, and to discuss your objectives.
If you are bringing a claim it makes sense to invest the time early on, because as soon as a claim is issued the court will impose a timetable that must be complied with. If you are not properly prepared in advance, you may be called away from your business for considerable periods of time, and at very short notice.
If you are defending a claim time may be even more restricted, so put some work in as soon as possible. This will allow your solicitor properly to evaluate the strength of your position, and could influence the strategies he (or she) suggests for resolving the situation.