If the setting “Open Gestimer at login” doesn’t work then you can add Gestimer to the login items in System Preferences > Users & Groups > Login items.
Use the little ‘+’-button or drag Gestimer from Finder (/Applications folder) to add Gestimer to the login items.
A future update will allow you to change the notification sound.
For now you might find it useful to enable the option to flash your screen when you get an alert. Open System Preferences > Accessibility > Audio:
Reminders may take a few minutes to synchronize. Since the app writes to the Reminders database, Gestimer has no control over when reminders are synchronised.
Double-check that you have the Sync using Reminders option enabled under Gestimer’s settings.
Gestimer is for short-term reminders, things you want to quickly forget about, i.e. for reminders within the next 5–8 hours. Calendar or todo apps are better suited for tasks that occur in the longer-term.
Additionally, increasing this limit would make it difficult to set accurate reminders.
Currently, you have to create a new reminder and delete the old one. A future update will allow you to edit an existing reminder. Editing reminders needs to be fun (just like the app itself) which is why implementing this takes a bit longer.