There’s no right answer for number of inquiries. But if you start seeing denials I’d suggest stopping.
As an observation, I’d caution against applying for the sake of applying. Make each card count for you either with bonuses, cash back, benefits, long term strategy, etc.
Racking up a ton of cards will allow them to age together which in the long term will be beneficial to you. Definitely nurture the ones you have especially the Discover as SP CLIs are possible in the future.
Beware of Comenity as they can be a jealous, fickle beast. Also, note secured card issuers monitor your credit as well.
I guess my concern is I don’t want what you do now to stifle you in the future. With a short amount of time 3-6 months and the right utilization, your scores will flourish.
Now to not be the person in a glass house throwing stones, I did a couple of mini-sprees last year when my beginning scores were lower (see signature) but initially I spaced them out at 90 day intervals. Picked up 4 in Aprill...waited 90 days. Picked up one in July...waited 90 days. Picked up a hidden Amex (2 months) and two more...waited, okay, after that I went a little crazy and didn’t wait much.
All that is to say make sure you have a strategy in place for the long-term. Also, make sure the cards you have work for you and aren’t just place holders. Kudos to you in your journey thus far and welcome to the boards.
Also, I’m intrigued by your Target Card. Care to indulge me on your starting limit. I have that card and it’s been stuck at $500 for what feels like a millennia.