If you are planning to attend the conference as a standard delegate (i.e. not a presenter), there is no deadline for registration. As long as space is available at the conference, you can register right up until the conference itself. Do check the homepage of the conference website for announcements about the conference being/becoming fully booked. However, if you know you are going to attend, we do recommend that you do it as early as possible. As well as ensuring your place, this will mean that the conference secretariat will be able to send all the relevant documentation to you in good time before the conference, and your name will be added to the published list of participants.
If you are making a presentation at the conference, it is essential that you register according to the author registration deadline which is detailed in your acceptance correspondence. If you do not register by this date, your material will be automatically excluded from the final conference program.