Flip's first short was Fiddlesticks, a two-strip Technicolor cartoon released in August 1930. The frog appeared in 38 shorts before making his final curtain call in Soda Squirt, a short released in October 1933.
Here's a couple of Hollywood trade ads, from March 1931, and April 1931, respectively. I love Ub's self portrait in the second ad.
Iwerks returned to the Disney Studio in 1940 where he excelled in all things technical. As always, click on the images to make them bigger.