trying to identify one bar to the left and one bar to right of a selected bar using input.time in pinescript - label

Question

hoping someone can help me with what should be simple but I can't seem to find a solution.
Using input.time/confirm=true, i select a bar on the chart
I would like to print a label on the selected bar, on the bar to the left and on the bar to the right.
The issue I think is that input.time is not compatible with a simple +/-1 so I think it needs to be converted to a bar index. I've tried doing that in the code below but it still doesnt seem to work
The reason for creating this code is to ultimately get the system to determine if the selected bar is a pivot and then based on that do other things. This was just the first step so I can understand what I'm doing wrong.
Any assistance appreciated!
//#version=5
indicator("My script", overlay = true)
start_time = input.time(timestamp("20 Jan 2021"), "Start Calculation", confirm=true)
start_bar = bar_index[start_time]
// Add label above the selected bar
label.new(x=start_time, y=high[start_bar], text='Selected bar', color=color.white, xloc=xloc.bar_time, yloc=yloc.abovebar)
// Add label above the bar to the left of the selected bar
label.new(x=time[start_bar-1], y=high[start_bar-1], text='Bar left', color=color.white, xloc=xloc.bar_time, yloc=yloc.abovebar)
// Add label above the bar to the right of the selected bar
label.new(x=time[start_bar+1], y=high[start_bar+1], text='Bar right', color=color.white, xloc=xloc.bar_time, yloc=yloc.abovebar)
using this code the selected bar correctly display's its label - but the left and right bars are completely off ...
enter image description here

Answer 1

Like this:
//#version=5
indicator("My script", overlay = false)
start_time = input.time(timestamp("8 Jan 2023"), "Start Calculation", confirm=true)
var int barStart = 0
if time == start_time
barStart := bar_index
if barStart
var l1 = label.new(x=barStart, y=high, text='Selected bar', color=color.white)
// Add label above the bar to the left of the selected bar
var l2 = label.new(x=barStart-1, y=high, text='Bar left', color=color.white)
// Add label above the bar to the right of the selected bar
var l3 = label.new(x=barStart+1, y=high, text='Bar right', color=color.white)
If you need time coordinate, then you can use timeframe.in_seconds() with current chart's timeframe, and then add resulted value to the start_time, so it will be +1 bar.