ovulation window?

My husband and I decided we wanted to start trying for a baby this month, I got an app to show me when my ovulation window is open and it starts today-Sunday. He is having to be gone Friday-Sunday. Has anyone conceived in their early days of ovulation? Also I did the due date calendar and it goes by the first day of your last period but does anyone have a guess of when I'll be due is we conceive this week? Thank you for all the help, I'm trying not to tell anyone we are trying for baby #1.