It depends. Do you have another title in mind for your proposed article? If so, give your first magazine two months to respond and then mail off an inquiry letter. If you have only one publication as a target then you can wait a little longer than two months. In today’s market, though, you may not receive any reply, to your first letter or your second. I know that sounds terrible but I’m being realistic. Editors are busy and they are swamped. There are things you can do while you’re waiting.
The first thing is to keep at it! Keep writing, even if it is only for your own blog. Keep researching new topics. Send letters to a newspaper editor. Offer to write for your home town weekly. Keep reviewing freelance job sites and Craigslist. Don’t sit by the mailbox waiting for just one query to bear fruit. Plant a dozen trees while you wait for one to grow. I do have some practical advice.
Many editors still allow queries and materials in hardcopy. A few, but some, like National Geographic Traveler and Outside Magazine. These people require an SASE if you want a reply. For those companies, you can send your materials by UPS with a postage paid return envelope. Make sure the return envelope has tracking. You’ll get an e-mail if that letter starts its way back to you. That may be a way to know when your query has been rejected. Or, accepted, perhaps. Also, when you write your follow on letter, you will have a tracking number to give them. Less chance of them losing your materials in the mailroom. Good luck.