When should I have the 500,000 baht in my checking account when traveling outside and returning to Thailand?

Hello, I already have a DTV. I just wanted to know when I'm traveling outside of Thailand and returning, when should I have the 500,000 baht in my home currency in my checking account? Since interest rates in my country are very high, I always have to keep the money invested in government bonds to avoid losing value and melting away. But I'm worried that immigration might ask for it and I don't have it in my checking account. How does that work? When do they ask to check? Thank you very much.