The major baseball card companies such as Topps, Panini, and Leaf all begin releasing their new baseball card products starting in late January and continuing through the summer. Here are some more specifics on the release timelines:

Topps is generally the first company to release new baseball cards each year. They will start with the flagship Topps Series 1 release, usually coming out in late January or early February. This is the main base set release that contains photos and statistics for players from the previous MLB season. Series 1 will be found in retail packs, blasters, hobby boxes, and high-end products.

In March, Topps then follows up Series 1 with the release of their annual Heritage High Number product. This set highlights retired players and parallels/short prints of current stars. Heritage uses a retro design inspired by baseball cards from the 1950s/60s. Also in March, Topps Update begins arriving with rookie cards and any statistics/team changes from Spring Training.

April and May see Topps release their Series 2 and Series Highlights/Allen & Ginter products. Series 2 has more current player photos while Highlights/A&G go with fun vintage-style designs on top rookie cards and star veterans. Topps Traded comes out in July, spotlighting new acquisitions from the MLB trade deadline.

Panini also jumps into the yearly baseball card race in February/March with their Donruss and Donruss Optic releases. These products will feature the same rookie class and stars as Topps but with a more photo-centered graphic style. Panini then rolls out more hit-focused products like Contenders and Prizm through the spring/summer months.

Leaf is another issuer coming to market in March/April with their Leaf Metal, Leaf Greatest Hits and high-end Autographed Football/Basketball/Baseball sets. These sets highlight rare parallels, vintage design blends and coveted on-card autographs of the biggest names in the sport.

Beyond the major brands, there are dozens of smaller companies that debut new baseball sets year-round as well. Some focus more on specific player tiers like prospects, rookies or veterans. Others experiment with innovative serial-numbered parallels or unique memorabilia relic cards. Many will release box breaks, case breaks and single packs/boxes online throughout the baseball season too.

In summary, January through July/August are the primary months when new baseball card products for the upcoming MLB season begin arriving in stores, online card shops and break/rip websites. Release timelines may vary slightly year to year. The flagship releases are usually the best first chance for collectors to add rookie cards and stars to their collections each spring before the action on the diamond begins anew. Careful planning of shopping and collecting budgets will serve enthusiasts well in chasing the hot new baseball cards arriving weekly throughout the issue cycle. Let me know if any part of this overview on baseball card release dates needs further explanation or expansion.