When traveling to China, an advance visa is always necessary. A visa on arrival will not be issued at any Chinese land border.
You should apply for a Chinese visa in your home country and not in a third country on the way to China (which has become increasingly difficult in resent years, depending on the country of application). Once the Chinese tourist visa is issued, you have 90 days to enter China. For example you plan to enter China on September 15; in this case, the earliest application date for your China visa is June 15. Exeptions to this rule are made for business visa holders who can apply for their business visa six month prior to the planned entry. Please note that in some countries it is not possible to apply for a Chinese visa if you are not a resident of this country. For example, its not possible to apply for a Chinese visa at the Chinese embassy in Kyrgyzstan if you are not a resident of Kyrgyzstan or have lived there for at least six month and hold a residence permit. In 2019 it was very easy to apply for a Chinese visa in Tbilisi (Georgia) on the way to China, even for non-residents (however, this can change any time). We need your Chinese visa scan at least 35 days in advance (before you enter as a China Overland traveller with your own vehicle).