IUD strings and when when to have sex?

OK, so I got the Skyla on the 11th of July, and the doctor said to come back in a month so she can check the strings. I have an appointment for the 15th of August, but was visiting my boyfriend next weekend (we're in an LDR) and sex is definitely a possibility. Should I have sex before the strings are checked? I was planning on using condoms anyway, if that affects anything.