We can apply for a study visa if student are planning to come to Ireland to undertake a course of study for more than 3 months.
Study visa has to be applied up to 3 months before the date of travel to Ireland.
View Details http://www.inis.gov.ie/en/INIS/Pages/Study
Applicant can apply for an Employment visa after they have obtained your employment permit from the Department of Jobs, Enterprise & Innovation (DJEI).
Applicant can apply for an Employment (Permits etc.) visa up to 3 months before your date of travel to Ireland.