How can I adjust my calendar so ADHD doesn’t make me extremely early or late
Many adults with ADHD find that no matter how carefully they plan, they still arrive either far too early or frustratingly late. This pattern is not a sign of poor discipline. It reflects the way ADHD affects how the brain perceives time, plans ahead, and handles anxiety about punctuality. According to NICE guidance on ADHD, challenges with time perception, organisation and task management are core features of the condition and can cause real difficulties with work, appointments and daily routines.
Understanding ADHD and time perception
Research consistently shows that adults with ADHD have measurable differences in how they experience and estimate time. A 2022 study in Frontiers in Human Neuroscience found that adults with higher ADHD symptoms struggled with time estimation and remembering to act at specific times, both key to punctuality. A 2023 review of adult ADHD time perception studies also confirmed that people with ADHD often underestimate durations and misjudge when to begin tasks, contributing to chronic lateness or overcompensation by arriving far too early.
NHS psychoeducational materials explain that these time-tracking issues are linked to executive-function difficulties such as poor working memory, reduced attention control and problems switching between tasks. When combined with anxiety about being late, this can cause a “push and pull” pattern where a person either rushes at the last minute or leaves hours early to avoid stress.
Mechanisms behind being early or late
People with ADHD often describe time as moving “too fast” when they are engaged and “too slow” when they are bored. This fluctuating sense of time makes it hard to judge when to start getting ready or how long something will take. As the NHS explains, the ADHD brain tends to focus on the present moment, which can shorten the “time horizon” needed to plan ahead effectively. Emotional responses also play a role: anxiety and shame about past lateness can drive people to arrive excessively early, while distraction or hyperfocus can make them lose track of time until it is almost too late.
Practical calendar and planning adjustments
Experts recommend using structured, external tools to make time more visible and predictable. NHS-aligned guides suggest adding buffer blocks into your calendar rather than just the appointment itself. For example, if a meeting starts at 10 a.m., schedule a “get ready” reminder for 9 a.m. and a “leave now” alert for 9.30 a.m. Using multiple alarms helps compensate for what researchers call prospective timing deficits, the ability to remember to act at a specific future time.
Visual aids like digital calendars, colour-coded schedules and visible clocks in different rooms can further reduce reliance on internal time sense. The CNWL NHS ADHD Adjustments Guide also recommends using smartphone reminders, apps that display countdowns, and written checklists for daily routines. CBT-based strategies such as “reverse scheduling”, which involves planning backwards from the time you need to arrive, can make buffer times more realistic and help avoid last-minute panic.
Structured support can make a difference too. Services like Theara Change offer behavioural coaching and therapy-based programmes that teach adults with ADHD how to externalise time, set realistic expectations, and build consistency using calendars and reminders.
Key takeaway
Being chronically early or late is a well-recognised effect of ADHD, caused by differences in time perception and executive functioning rather than lack of effort. According to NHS and NICE guidance, the best approach combines medication, CBT-style time-management skills and consistent use of digital tools that make time tangible and predictable. By building visible schedules and using reminders strategically, adults with ADHD can find a balanced rhythm, arriving on time without the stress of rushing or waiting for hours.
