Hi Iman

I think the important thing is to collect data on a cohort, or group of individuals all born in the same time period, it is better to start with egg stage but in some condition you can omit egg period. For example I had studied sub-lethal effects of Beauveria on life table parameters of Tetranychus urticae from larval stage because in most cases entomopathogenic fungi haven’t effect on egg stage; you can check it at https://www.researchgate.net/publication/236165699_Sublethal_effects_of_Beauveria_bassiana_on_life_table_parameters_of_twospotted_spider_mite_Tetranychus_urticae_%28Acari_Tetranychidae%29

Article Sublethal effects of Beauveria bassiana on life table parame...

Depending on the organism, you may or may not see egg laying/development/hatching.  In our life table study of an insect parasitoid all we could see was oviposition of the egg into the host and then adult parasitoid emergence from the host.  Thus, we quantified the duration of "pre-imaginal development" and recorded the surviorship of that "stage".  So it is possible to group life stages and still get a complete life table.  See the publication link below.

Article Development and Reproduction of a Population of Eretmocerus ...

When the aim of study include the life period in egg , in this case we can not ignore it , beside that most lethal gene effect on embryonic development in egg so embryonic mortality is important to detect lethal genes

Good Luck