Upvote:3
You can enter at any point during the three-month period of validity.
With some countries, you must leave the country before the visa expires. With others, you only need to enter before the visa expires. If your delayed travel plans mean that you wish to remain in Egypt after the expiration date of the visa, you'll need to find out which kind of country Egypt is. If you plan to depart before the visa expires in any case, then you don't need to worry about this.