Do the following sentences sound natural? In a business situation, 一日 [the 1st date of month] is commonly pronounced いっぴ[ippi] instead of ついたち[tsuitachi]. This is not because the pronunciation いっぴ[ippi] is politer than ついたち[tsuitachi], but just because it’s prevailing custom in business. If not, could you please correct it in the way you would say?