No. The 12 month time frame doesn't reset if you transfer your Lifetime ISA to another provider. You can use your Lifetime ISA to buy your first home 12 months after your first payment into the Lifetime ISA.
This is only the case if you allow your transfer to complete before you add any additional funds into the account. If you add any money into the account before the transfer completes, the date you opened your Tembo account will be the new opening date for the entire account, including the funds transferred.
Also: if you're a Tembo Savings customer, you get fee-free access to our award-winning mortgage advice service when you come to buy your first home!