Pregnancy after mirena removal

I'm 35 (almost 36) with 3 teenagers and my husband has finally agreed to go for #4.  I had my mirena removed on August 11th after having one for over 13 years. I had some VERY light spotting (no pad/tampon necessary) for 3 days starting on September 1st. Still no AF. All of my other pregnancies just happened and this is our first time "trying". When should I expect AF to return? Should I test yet?