There are time limits for anything that you can apply to the Employment Tribunal for. Most of these limits are quite strictly enforced but can exceptionally be extended. You should always make sure that you stay well within the time limits for making an application.
ACAS conciliation will have the effect of extending the date that you need to make your application.
If you receive ‘Orders’ or ‘Directions’ from the Tribunal you should make sure that you comply with them before the time limit set. If for any good reason you know that you will be late complying with Orders you should tell the Employment Tribunal and the other side as soon as you know. You also need to explain the reason why you will be late.