How to get wiremock running before the spring boot application status up?

you might create static instance of WireMockServer in your test. Here is a code sample:

@RunWith(SpringRunner.class)
@SpringBootTest
public class YourApplicationTests {
    static WireMockServer mockHttpServer = new WireMockServer(10000); // endpoint port here

    @BeforeClass
    public static void setup() throws Exception {
        mockHttpServer.stubFor(get(urlPathMatching("/")).willReturn(aResponse().withBody("test").withStatus(200)));
        mockHttpServer.start();
    }

    @AfterClass
    public static void teardown() throws Exception {
        mockHttpServer.stop();
    }

    @Test
    public void someTest() throws Exception {
        // your test code here
    }
}

The Spring Boot team have built a WireMock integration. Might be worth checking it out rather than rolling your own: http://cloud.spring.io/spring-cloud-static/spring-cloud-contract/1.1.2.RELEASE/#_spring_cloud_contract_wiremock