A few more things to consider when planning a party
Time and length of your party: For a toddler, I wouldn't go beyond 3 hours of party time. Choose a time of day that your toddler is at his happiest - most toddlers will have a midday sleep so a lunch time party is really out of the question. Mid-morning or mid-afternoon are ideal party times for this age group. Try to wind things down by about 4pm in order to calm the kids and start your normal dinner, bed, bath time routine.
Gift Opening: This is totally up to you but toddlers can get a bit rowdy around presents, especially when their peers are around. I have always found it best to open gifts at home, in a calm space where your toddler can take as much time as he or she needs to enjoy the moment.
Toddler input: By the age of 3 your toddler will be very happy to participate in planning his or her party which can be lots of fun for you both - involve them as much as possible to make their day extra special and all about them.
Enjoy the day, plan ahead to limit stress and remember that this day really is all about your little lady / guy. Take the time to reflect, soak it all in and get ready for another year of deliciousness with your little person.