I want the $30 discount, but am not ready to complete my return. My husband and I are also discussing filing separately as I am self-employed and he is not. It looks like it might be the better option for us.
Yes, you can pay now to lock in the current price, and finish filing your taxes at a later date.
Please refer to this TaxPro's response to a similar scenario of deciding whether to file MFJ or MFS when one of you is self-employed (the special rules are still the same for tax year 2017): https://ttlc.intuit.com/replies/5902608