1) Yeast need oxygen at the start of fermentation and 2) you have some indication that fermentation has started,. If the airlock is bubbling, you have CO2 generation and any oxygen in the headspace has been displaced by the CO2.
When you really need to worry about oxidizing your brew is after fermentation is well under way or complete, and even then it would be along the lines of aerating your cider not just drying out the airlock or opening it to check gravity.
I think it's fine. RDWHAHB
(it's what I'd do in your shoes.)