TTC baby #2

With my first it was totally by surprise and was not planned at all, she is almost 2 now and my husband and I want to try for another i am expected to get my period on the 26th and I am 5 dpo. How long should I wait to test? And any other success stories from TTC your first month and getting pregnant. I'm really hopeful because I know last time we didn't try so I feel now that we are trying I should get it the first try and I feel I will be extremely heartbroken if we don't :(