I put from the beginning, but it depends on the couple. My Man and I were having sex for decades
before we brought in sex toys. We did NOT have a problem with "fizzling" or anything. But, due to early perimenopause I started having issues having an orgasm. I had never had any problem before, and naively thought sex toys were for (don't shoot me) lesbians and old maids.
We discovered that with sex toys, I not only could have an easier time with orgasm (along with a well thought out HRT program) but we found things to do in bed we had never thought of before!
All that time wasted. OK, not "wasted" we had a [italic]great] sex life before we found toys. I wish we had used sex toys earlier in our relationship. I was the one who didn't want to use them. Go figure.
But, we're having a great time, now and we always have. Sex was always good for us. But, the toys often add something to the experience. We still have sex with no toys at least a few times a week, too.