Should I apply now?

Hello! I am in the process of gathering documents for applying for a visa. I was going through the application and found that in section 2.2, you choose which type of L you need. Our trip is late October, and it is early June, so I need a single entry that is valid for 6 months, but there is only an option for single entry for 3 months. Should I wait to apply until it is less than 3 months or can I put "One entry valid for 6 months from the date of issue" in the "Other" section? Thanks!