Best time to post on Instagram?



Does anyone know any good apps/websites that tells you when the best time to post is? I’ve read articles but I want the best time for my account. 

I’ve been struggling with this forever. A friend just sent me this Instagram tool that automatically posts for you at the best time. I’ve seen a huge boost in engagement over the past week. I’m pretty sure it posts when the majority of your followers are online.

Sorry forgot to link it. iPhone app here