Once you have put in your application to the tribunal you will be waiting for the employer's response (ET3). This can take up to a month. Orders from the Tribunal with their deadlines will then usually follow.
You must read the tribunal's orders very carefully as tribunals are very strict in expecting that their decisions be complied with.
Diarise dates mentioned in the tribunal's orders and aim to have tasks completed ahead of time by at least a few days. Your employer's representatives will often lag behind schedule but try not to fall into this trap yourself.
If you are late you lay yourself open to costs. If the opposition is late they open themselves up to a 'preparation time order'. This is good to keep in mind but is less remunerative than a costs order. In any case your employer might have deep pockets. You most likely don't.
If you do mess up be ready with a good reason and an apology.