If you want to configure Full/Incremental/Continuous search crawl, follow below steps:
1. On the Configure Search Settings page, in the Crawl Settings section, click Content sources and crawl schedules.
2. On the Manage Content Sources page, right click the content source for which you want to schedule an incremental crawl and then click Edit.
3. On the Edit Content Source page, in the Crawl Schedules section, do the following:
Incremental/Full crawl setup:
If an Incremental/Full crawl has never been created for this content source, click the Create schedule link below the Incremental/Full Crawl list.
If you are changing the Incremental/Full-crawl schedule, click the Edit schedule link below the Incremental Crawl list.
1. In the Manage Schedules dialog box, in the Type section, select Daily, Weekly, or Monthly.
2. In the Settings section, do the following:
2.1 In the Run every box, type the number of days between crawls. For example, to schedule an incremental crawl to start every other day, type 2.
2.2 In the Starting time list, select the time of the day from which to start the scheduled crawl.
2.3 If you want to crawl more frequently than once a day, select the Repeat within the day box and type the number of minutes to wait between crawls in the Every box and type the total number of minutes in which to repeat the crawl within the same day in the For box. For example, if you select Repeat within the day and type 60 in the Every box and 720 in the For box, an incremental crawl of the content source you are configuring starts every 60 minutes up to 720 minutes (12 hours) after the first scheduled incremental crawl for this content source ran.
2.4 Click OK.
3. Click OK in Content Source page.
Continuous crawl setup:
1. Select the continuous crawl radio button in Crawl Schedule Section.
2. Click OK in Content Source page.
To Change the Continuous crawl time do the following steps:
Verify that the user account that is performing this procedure is a member of the Farm Administrators group.
1. Start a SharePoint 2013 Management Shell.
2. In Windows PowerShell command prompt, type the following commands:
Where "n" is the regular interval in minutes at which you want continuous crawls to start. The default interval is every 15 minutes. The shortest interval that you can set is 1 minute.
If you reduce the interval, you increase the load on SharePoint and the Crawler. Make sure that you plan and scale out of resources accordingly for this increased consumption .