Technically, you'll start to see results right away; however, it takes time for a campaign to "normalize" to the point of understanding how it will perform long term.
Avoid sending hot leads to competitors and gain extra data for optimization opportunities.
DSA Campaigns are used as learning experiments - You may choose to build dynamic search ad campaigns because they help you learn what ad copy & keywords to use in the other campaigns, in case you missed any important and effective words.