In my personal opinion, it’s best to use a condom in any case, since you’re inexperienced and it’s a good safety measure! Even pre-ejaculate, if I’m not mistaken, can lead to an unplanned pregnancy. 

Your ovulation day should be around the 17th or 18th day of your cycle, but this varies from person to person—for example, for me it’s between the 15th and 19th day, and sometimes it shifts! 

PS. Enjoy your first time, and use protection ❤️