There's really no steadfast rule as far as when is the right time. You can bring it up in conversation and get your boyfriend's opinion on it and then go from there, or you can wait until you think the moment is right and pull something out. If you're going to surprise him with a toy, make sure that at the very least it can be used on both of you. I'd try to talk to him about it first

Whenever your comfortable enough

It's only too soon if you haven't discussed it at all yet.

From a guys perceptive, just bring it up and see what he says. Or just pull out a toy and let him use it on you. Unless you want to use toys for couples. But having a conversation about it can't hurt.

I agree. It would really depend on the relationship. I like the suggestion of bringing up toys in casual conversation to see how he reacts. If he reacts positively, talk about incorporating them. Or you could always "accidentally" leave something sitting out next time he comes over and see what he says.

There are always new sex toys. Spicing things up later shouldn't be a problem as long as you're open to trying new things. You could play a game where you put something off limits for x amount of time, like hands-free foreplay or going without vaginal intercourse for two weeks. If you watch porn or read erotic literature or talk with your friends about sex, you can get ideas from them. There's an entire world of BDSM and kinks that you can dip your toes in or dive right into. Ask him what he fantasizes about, what he wants to try. Use your imagination. Communicate and have fun.

As long as you've discussed the idea and both consent then its whenever both are comfortable.