180 days:As far as I know, the rules are the same as for everyone else. You are only considered tax resident if you spend 183+ days per calendar year in Thailand.
Tax residents pay tax on their global income now. But if you spend less than 183 days there, no tax.
Thailand - Individual - Residence
Detailed description of individual residence rules in Thailand
taxsummaries.pwc.com
Also observe the PE rules, your company may be deemed having a PE earlier.