Ttc with a holiday booked and do winter children really care ?

So first of all is it a good idea to start ttc with a holiday booked ? 
​We planned on trying for our first next July but have a trip booked in September. Should I hold off trying ? And so with that being said if we hold off a tad we will fall into the winter and we didn't really want a winter baby only because of people have said but do winter children mind having Christmas and birthday all that the same time ?
​Thank you