By taping on three horizontal dots of a message, there is a "Schedule boost" item. Just tap on it.
https://cdn.masto.host/tootfedilabapp/media_attachments/files/115/074/263/059/832/091/original/f8a224aeef149036.png
With #Fedilab, you can schedule boosts. As this is still an in-app feature, this is done through your device.
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.