I was, doing my PHD regarding neonatal seizures before, however I've changed my research for infant pain recognition via image processing due to subject data and the equipment problems.  Based on the literature review there are plenty types of seizures and it required different duration of segmentation. However, from my experienced, EEG seizures signals segmentation was done based on the spike waves. Here I enclosed some of the papers for you

Thanks a lot Muhammad Naufal! I will try to look at the papers you recommended. I appreciate your efforts.

Typical EEG databases have 23.6 seconds epoch recorded at a sampling rate of 173 Hz. 

Thanks Aditya for your feedback. But is this 23.6 sec epoch for processing at a time or they further divide the 23.6 long sequence into smaller ones (few secs) for processing during seizure detection?

The whole epoch is used for processing (denoising and feature extraction)

As per ref , Neider Mayer’s Electroencephalography., edited by Donald L Schomer,Fernando H.Lopes da silva, time period for clinical purpose can be taken as 5 sec-10sec.

Usually one second epochs are used in seizure detection.There are papers with 2 sec and 3 sec also.