pre-engage
/ˌpriːɪnˈɡeɪdʒ/ /ˌpriːɛnˈɡeɪdʒ/ /ˌpriːɪŋˈɡeɪdʒ/verb
1To put under an obligation or commitment beforehand; to bind in advance by a pledge or promise. In later use especially: to secure the services of.
2In pass. To be previously or already engaged to be married. Also refl. in same sense.
3To secure for oneself or take possession of beforehand; to reserve in advance.
4 [with object] (In pass.). To be informally committed to getting engaged to be married.
Origin
Mid 17th century; earliest use found in James Shirley (bap. 1596, d. 1666), playwright and poet. From pre- + engage.