Prepares an oven, as for baking

• Gives advance warming
• Prepares for cooking, as an oven
• Warms in advance
• Prepares an oven before baking
• Readies the oven
• Warms an oven
• Warms up ahead of time
• Gets ready, as an oven

Wiktionary Word definitions in Wiktionary
vb. (en-third-person singular of: preheat )